test: allow a repo-root level "pytest -n6" to succeed.

the fixtures from chatmaild and cmdeploy test plugins were clashing.

.github/workflows/ci.yaml

@@ -29,7 +29,7 @@ jobs:
           ref: ${{ github.event.pull_request.head.sha }}
           persist-credentials: false
       - name: download filtermail
-        run: curl -L https://github.com/chatmail/filtermail/releases/download/v0.7.1/filtermail-x86_64 -o /usr/local/bin/filtermail && chmod +x /usr/local/bin/filtermail
+        run: curl -L https://github.com/chatmail/filtermail/releases/download/v0.7.4/filtermail-x86_64 -o /usr/local/bin/filtermail && chmod +x /usr/local/bin/filtermail
       - name: run chatmaild tests 
         working-directory: chatmaild
         run: pipx run tox

.github/workflows/docs-preview.yaml

@@ -13,6 +13,11 @@ jobs:
   scripts:
     name: build 
     runs-on: ubuntu-latest
+    env:
+      # Pin the repository links in the docs to this pull request's head commit
+      # so that linkcheck resolves files which only exist on the branch so far.
+      # see doc/conf.py
+      DOC_GITHUB_REF: ${{ github.event.pull_request.head.sha }}
     environment:
       name: 'staging.chatmail.at/doc/relay/'
       url: https://staging.chatmail.at/doc/relay/${{ steps.prepare.outputs.prid }}
@@ -51,7 +56,7 @@ jobs:
           mkdir -p "$HOME/.ssh"
           echo "${{ secrets.CHATMAIL_STAGING_SSHKEY }}" > "$HOME/.ssh/key"
           chmod 600 "$HOME/.ssh/key"
-          rsync -rILvh -e "ssh -i $HOME/.ssh/key -o StrictHostKeyChecking=no" $GITHUB_WORKSPACE/doc/build/ "${{ secrets.USERNAME }}@chatmail.at:/var/www/html/staging.chatmail.at/doc/relay/${STEPS_PREPARE_OUTPUTS_PRID}/"
+          rsync -rILvh -e "ssh -i $HOME/.ssh/key -o StrictHostKeyChecking=no" $GITHUB_WORKSPACE/doc/build/ "${{ secrets.USERNAME }}@chatmail.at:${STEPS_PREPARE_OUTPUTS_PRID}/"
         env:
           STEPS_PREPARE_OUTPUTS_PRID: ${{ steps.prepare.outputs.prid }}
 

.github/workflows/docs.yaml

@@ -47,5 +47,5 @@ jobs:
           mkdir -p "$HOME/.ssh"
           echo "${{ secrets.CHATMAIL_STAGING_SSHKEY }}" > "$HOME/.ssh/key"
           chmod 600 "$HOME/.ssh/key"
-          rsync -rILvh -e "ssh -i $HOME/.ssh/key -o StrictHostKeyChecking=no" $GITHUB_WORKSPACE/doc/build/ "${{ secrets.USERNAME }}@chatmail.at:/var/www/html/chatmail.at/doc/relay/"
+          rsync -rILvh -e "ssh -i $HOME/.ssh/key -o StrictHostKeyChecking=no" $GITHUB_WORKSPACE/doc/build/ "${{ secrets.USERNAME }}@chatmail.at:"
 

CHANGELOG.md

@@ -1,5 +1,60 @@
 # Changelog for chatmail deployment
 
+## [1.12.0] - 2026-07-31
+
+### Breaking Changes
+
+- [**breaking**] Introduce configurable system limits to reject new address creation and limit imap/smtp connections.
+  Dovecot default connection limit lowered from 50k to 10k,
+  Postfix default connection limit lowered from 5k to 1k,
+  larger relays need to adjust their settings.
+
+### Features
+
+- Reduce maximal_queue_lifetime from 5d to 2d
+- Disable negative cache in unbound (#992)
+- *(mtail)* Add incoming_mailer_daemon_mail_count
+- *(postfix)* Disable processing of MIME headers
+- *(dovecot)* Advertise privacy_mail as admin contact, drop server comment
+
+### Bug Fixes
+
+- Set relay restrictions per smtpd service with default reject
+- Reduce maxproc for filtermail-transport LMTP client to 500
+- Core 2.50.0 does not have delete_server_after config anymore.
+- Check if all required ports are available for filtermail (#983)
+- Always deploy unbound.conf.d/chatmail.conf (#993)
+- Expire empty directories (#994)
+- Crypt-r dependency was declared for wrong Python version
+- Always overwrite /etc/resolv.conf, even if it is a symbolic link
+- Pass kwargs to files.put()
+- List Iroh proxy endpoints used by 0.35 and 1.0, drop stale /relay/probe from earlier versions
+- Fix port discovery when ss -tulpn shows dovecot before stats
+
+### Documentation
+
+- Add scripts/initenv.sh to upgrade instructions
+- Update overview diagrams (#995)
+- *(overview)* Remove mermaid styles from 'Accepting and delivering mail' (#1009)
+- *(README.md)* Clarify security enforcement (#1011)
+
+### Miscellaneous Tasks
+
+- *(ci)* Auto-trigger docker build on release tag push
+- *(acmetool)* Update let's encrypt ToS link to 1.8
+- *(ci)* Update doc staging upload path
+- *(ci)* Fix docs upload path
+
+### Refactor
+
+- *(postfix)* Remove unused "filter" lmtp service
+- Install dns-root-data instead of using unbound-anchor
+- *(deps)* Remove domain-validator dependency
+
+### Testing
+
+- Set socket security for IMAP and SMTP to "TLS" in "dclogin"
+
 ## [1.11.0] - 2026-05-15
 
 ### Breaking Changes

CONTRIBUTING.md

@@ -5,3 +5,6 @@ We use [git-cliff] to generate the changelog from commit messages before the rel
 
 [Conventional Commits]: https://www.conventionalcommits.org/
 [git-cliff]: https://git-cliff.org/
+
+To update client app version information,
+edit [chatmaild/src/chatmaild/defaults/appversions.json](chatmaild/src/chatmaild/defaults/appversions.json).

README.md

@@ -1,19 +1,24 @@
 
 # Chatmail relays for end-to-end encrypted email
 
-Chatmail relay servers are interoperable Mail Transport Agents (MTAs) designed for: 
+Chatmail relay servers are interoperable Mail Transport Agents (MTAs) designed for:
 
 -  **Zero State:** no private data or metadata collected, messages are auto-deleted, low disk usage
 
 -  **Instant/Realtime:** sub-second message delivery, realtime P2P
    streaming, privacy-preserving Push Notifications for Apple, Google, and Huawei;
 
--  **Security Enforcement**: only strict TLS, DKIM and OpenPGP with minimized metadata accepted
+-  **Security Enforcement**: Only connections with strict TLS are accepted;
+   all messages must be correctly signed with DKIM and OpenPGP-encrypted with minimized metadata.
+   There are experimental exceptions for no-DNS relays,
+   which are allowed use self-signed TLS certificates
+   and which do not need to DKIM-sign their messages.
+   Unencrypted messages are allowed in neither case.
 
 -  **Reliable Federation and Decentralization:** No spam or IP reputation checks, federating
    depends on established IETF standards and protocols.
 
-This repository contains everything needed to setup a ready-to-use chatmail relay on an ssh-reachable host. 
+This repository contains everything needed to setup a ready-to-use chatmail relay on an ssh-reachable host.
 For getting started and more information please refer to the web version of this repositories' documentation at
 
 [https://chatmail.at/doc/relay](https://chatmail.at/doc/relay)

RELEASE.md

@@ -1,15 +1,13 @@
 # Releasing a new version of chatmail relay
 
-For example, to release version 1.9.0 of chatmail relay, do the following steps.
+For example, to release version 1.13.0 of chatmail relay, do the following steps.
 
-1. Update the changelog: `git cliff --unreleased --tag 1.9.0 --prepend CHANGELOG.md` or `git cliff -u -t 1.9.0 -p CHANGELOG.md`.
+1. Update the changelog: `git cliff --unreleased --tag 1.13.0 --prepend CHANGELOG.md` or `git cliff -u -t 1.13.0 -p CHANGELOG.md`.
 
 2. Open the changelog in the editor, edit it if required.
 
 3. Commit the changes to the changelog with a commit message `chore(release): prepare for 1.9.0`.
 
-3. Tag the release: `git tag --annotate 1.9.0`.
+4. Open a PR with the new commit, merge it to main after review.
 
-4. Push the release tag: `git push origin 1.9.0`.
-
-5. Create a GitHub release: `gh release create 1.9.0`.
+5. In the web interface, create a GitHub release, tell it to create a new tag.

chatmaild/MANIFEST.in

@@ -1,3 +1,4 @@
+include src/chatmaild/defaults/*.json
 include src/chatmaild/ini/*.ini.f
 include src/chatmaild/ini/*.ini
 include src/chatmaild/tests/mail-data/*

chatmaild/pyproject.toml

@@ -8,6 +8,7 @@ version = "0.3"
 dependencies = [
   "iniconfig",
   "filelock",
+  "psutil",
   "requests",
   "crypt-r >= 3.13.1 ; python_version >= '3.13'",
 ]

chatmaild/src/chatmaild/config.py

@@ -75,6 +75,16 @@ class Config:
         self.privacy_pdo = params.pop("privacy_pdo", None)
         self.privacy_supervisor = params.pop("privacy_supervisor", None)
 
+        self.max_load_1m = float(params.pop("max_load_1m", 5))
+        self.min_available_memory_mb = parse_size_mb(
+            params.pop("min_available_memory", "200M")
+        )
+        self.min_free_disk_space_mb = parse_size_mb(
+            params.pop("min_free_disk_space", "1G")
+        )
+        self.max_imap_connections = int(params.pop("max_imap_connections", 10000))
+        self.max_smtp_connections = int(params.pop("max_smtp_connections", 1000))
+
         # TLS certificate management.
         # If tls_external_cert_and_key is set, use externally managed certs.
         # Otherwise derived from the domain name:

chatmaild/src/chatmaild/defaults/appversions.json

@@ -0,0 +1,15 @@
+{
+  "clients": [
+    {
+      "clientId": "deltachat",
+      "sources": [
+        {
+          "sourceId": "gplay",
+          "versionInteger": 757,
+          "versionString": "2.59.1",
+          "downloadUrl": "https://github.com/deltachat/deltachat-android/releases/download/v2.59.1/deltachat-gplay-release-2.59.1.apk"
+        }
+      ]
+    }
+  ]
+}

chatmaild/src/chatmaild/doveauth.py

@@ -14,6 +14,7 @@ except ImportError:
 from .config import Config, read_config
 from .dictproxy import DictProxy
 from .migrate_db import migrate_from_db_to_maildir
+from .syslimits import has_sufficient_resources
 
 NOCREATE_FILE = "/etc/chatmail-nocreate"
 VALID_LOCALPART_RE = re.compile(r"^[a-z0-9._-]+$")
@@ -147,6 +148,8 @@ class AuthDictProxy(DictProxy):
             return userdata
         if not is_allowed_to_create(self.config, addr, cleartext_password):
             return
+        if not has_sufficient_resources(self.config):
+            return
 
         lock = filelock.FileLock(str(user.password_path) + ".lock", timeout=5)
         with lock:

chatmaild/src/chatmaild/ini/chatmail.ini.f

@@ -42,6 +42,33 @@ mail_domain = {mail_domain}
 # minimum length a password must have
 #password_min_length = 9
 
+#
+# System resource limits
+#
+
+# The following three limits refuse creation of new addresses
+# while existing addresses keep working.
+# Rejections are logged by the doveauth service.
+
+# Maximum 1-minute load average, as reported by "uptime";
+# it counts processes waiting for disk I/O as well as for CPU.
+#max_load_1m = 5
+
+# Minimum memory available without swapping.
+#min_available_memory = 200M
+
+# Minimum free disk space on the file system holding the mailboxes.
+#min_free_disk_space = 1G
+
+# Maximum number of concurrent IMAP connections
+# (the Dovecot imap process limit).
+#max_imap_connections = 10000
+
+# Maximum number of concurrent SMTP connections
+# on each of the submission and smtps ports (the Postfix process limit).
+# A single client IP may use up to a fifth of this.
+#max_smtp_connections = 1000
+
 # Use externally managed TLS certificates instead of built-in acmetool.
 # Paths refer to files on the deployment server (not the build machine).
 # Both files must already exist before running cmdeploy.

chatmaild/src/chatmaild/metadata.py

@@ -1,8 +1,10 @@
+import json
 import logging
 import socket
 import sys
 import time
 from contextlib import contextmanager
+from importlib.resources import files
 
 from .config import read_config
 from .dictproxy import DictProxy
@@ -18,6 +20,18 @@ def turn_credentials(turn_socket_path):
             return file.readline().decode("utf-8").strip()
 
 
+def read_appversions(path):
+    try:
+        data = json.loads(path.read_bytes())
+    except FileNotFoundError:
+        return None
+    except (OSError, ValueError):
+        logging.exception(f"failed to read {path}")
+        return None
+    # the dict protocol is line-based, keep the value single-line
+    return json.dumps(data, separators=(",", ":"))
+
+
 def _is_valid_token_timestamp(timestamp, now):
     # Token if invalid after 90 days
     # or if the timestamp is in the future.
@@ -101,6 +115,7 @@ class MetadataDictProxy(DictProxy):
         self.iroh_relay = iroh_relay
         self.turn_hostname = turn_hostname
         self.turn_socket_path = turn_socket_path
+        self.appversions_path = files(__package__).joinpath("defaults/appversions.json")
 
     def handle_lookup(self, parts):
         # Lpriv/43f5f508a7ea0366dff30200c15250e3/devicetoken\tlkj123poi@c2.testrun.org
@@ -125,6 +140,9 @@ class MetadataDictProxy(DictProxy):
                         case "maxsmtprecipients":
                             # postfix default  (see "postconf smtpd_recipient_limit")
                             return "O1000\n"
+                        case "appversions":
+                            value = read_appversions(self.appversions_path)
+                            return f"O{value}\n" if value else "N\n"
 
         logging.warning(f"lookup ignored: {parts!r}")
         return "N\n"

chatmaild/src/chatmaild/syslimits.py

@@ -0,0 +1,32 @@
+"""Detect whether the system is at its limits."""
+
+import logging
+
+import psutil
+
+MB = 1024 * 1024
+
+
+def read_value(getter):
+    try:
+        return getter()
+    except Exception as e:
+        logging.warning("ignoring unreadable system limit: %s", e)
+        return None
+
+
+def has_sufficient_resources(config):
+    """Return False if load, memory or disk exceeds a configured limit."""
+    load = read_value(lambda: psutil.getloadavg()[0])
+    mem = read_value(lambda: psutil.virtual_memory().available // MB)
+    disk = read_value(lambda: psutil.disk_usage(str(config.mailboxes_dir)).free // MB)
+    if load is not None and load > config.max_load_1m:
+        msg = f"load avg {load:.2f} > {config.max_load_1m:.2f}"
+    elif mem is not None and mem < config.min_available_memory_mb:
+        msg = f"available memory {mem}MB < {config.min_available_memory_mb}MB"
+    elif disk is not None and disk < config.min_free_disk_space_mb:
+        msg = f"free disk {disk}MB < {config.min_free_disk_space_mb}MB"
+    else:
+        return True
+    logging.warning("registration rejected: %s", msg)
+    return False

chatmaild/src/chatmaild/tests/plugin.py

@@ -20,6 +20,10 @@ def make_config(tmp_path):
         basedir.mkdir(parents=True, exist_ok=True)
         overrides = settings.copy() if settings else {}
         overrides["mailboxes_dir"] = str(basedir)
+        # permissive resource limits so tests never depend on host load/memory/disk
+        overrides.setdefault("max_load_1m", "99999")
+        overrides.setdefault("min_available_memory", "0")
+        overrides.setdefault("min_free_disk_space", "0")
         write_initial_config(inipath, mail_domain, overrides=overrides)
         return read_config(inipath)
 
@@ -37,22 +41,22 @@ def ipv4_config(make_config):
 
 
 @pytest.fixture
-def maildomain(example_config):
+def example_maildomain(example_config):
     return example_config.mail_domain
 
 
 @pytest.fixture
-def testaddr(maildomain):
-    return f"user.name@{maildomain}"
+def testaddr(example_maildomain):
+    return f"user.name@{example_maildomain}"
 
 
 @pytest.fixture
-def gencreds(maildomain):
+def example_gencreds(example_maildomain):
     count = itertools.count()
     next(count)
 
     def gen(domain=None):
-        domain = domain if domain else maildomain
+        domain = domain if domain else example_maildomain
         while 1:
             num = next(count)
             alphanumeric = "abcdefghijklmnopqrstuvwxyz1234567890"

chatmaild/src/chatmaild/tests/test_appversions.py

@@ -0,0 +1,96 @@
+import json
+
+import pytest
+
+from chatmaild.metadata import MetadataDictProxy
+
+ALLOWED_URL_PREFIXES = (
+    "https://github.com/deltachat/",
+    "https://download.delta.chat/",
+)
+
+
+def check_string(value):
+    assert isinstance(value, str), value
+    assert value
+
+
+def check_version_integer(value):
+    # core parses this as u32, see https://github.com/chatmail/core/pull/8557
+    assert isinstance(value, int) and not isinstance(value, bool), value
+    assert 0 <= value < 2**32, value
+
+
+def check_appversions(data):
+    """Verifies the file the way core parses it.
+
+    core deserializes into typed structs and drops the whole payload
+    of a relay if a single value has an unexpected type,
+    while missing or misspelled keys silently turn into defaults.
+    """
+    assert set(data) == {"clients"}, data
+    assert isinstance(data["clients"], list)
+    assert data["clients"]
+    client_ids = []
+    for client in data["clients"]:
+        assert set(client) == {"clientId", "sources"}, client
+        check_string(client["clientId"])
+        client_ids.append(client["clientId"])
+        assert isinstance(client["sources"], list)
+        assert client["sources"]
+        source_ids = []
+        for source in client["sources"]:
+            assert set(source) == {
+                "sourceId",
+                "versionInteger",
+                "versionString",
+                "downloadUrl",
+            }, source
+            check_string(source["sourceId"])
+            source_ids.append(source["sourceId"])
+            check_version_integer(source["versionInteger"])
+            check_string(source["versionString"])
+            check_string(source["downloadUrl"])
+            assert source["downloadUrl"].startswith(ALLOWED_URL_PREFIXES)
+        # core takes the first matching source, later duplicates never surface
+        assert len(set(source_ids)) == len(source_ids), source_ids
+    assert len(set(client_ids)) == len(client_ids), client_ids
+
+
+@pytest.fixture
+def appversions():
+    # check the file which chatmail-metadata actually serves
+    path = MetadataDictProxy(notifier=None, metadata=None).appversions_path
+    return json.loads(path.read_text())
+
+
+def test_appversions_schema(appversions):
+    check_appversions(appversions)
+
+
+@pytest.mark.parametrize("value", [True, -1, 2**32, "754", 754.0, None])
+def test_version_integer_rejected(appversions, value):
+    appversions["clients"][0]["sources"][0]["versionInteger"] = value
+    with pytest.raises(AssertionError):
+        check_appversions(appversions)
+
+
+@pytest.mark.parametrize("key", ["clientId", "sources"])
+def test_misspelled_client_key_rejected(appversions, key):
+    client = appversions["clients"][0]
+    client[key + "s"] = client.pop(key)
+    with pytest.raises(AssertionError):
+        check_appversions(appversions)
+
+
+def test_duplicate_source_id_rejected(appversions):
+    sources = appversions["clients"][0]["sources"]
+    sources.append(dict(sources[0]))
+    with pytest.raises(AssertionError):
+        check_appversions(appversions)
+
+
+def test_foreign_download_url_rejected(appversions):
+    appversions["clients"][0]["sources"][0]["downloadUrl"] = "https://example.org/x.apk"
+    with pytest.raises(AssertionError):
+        check_appversions(appversions)

chatmaild/src/chatmaild/tests/test_config.py

@@ -30,9 +30,9 @@ def test_read_config_ipv4(ipv4_config):
     assert ipv4_config.mail_domain == "[1.3.3.7]"
 
 
-def test_read_config_basic_using_defaults(tmp_path, maildomain):
+def test_read_config_basic_using_defaults(tmp_path, example_maildomain):
     inipath = tmp_path.joinpath("chatmail.ini")
-    inipath.write_text(f"[params]\nmail_domain = {maildomain}")
+    inipath.write_text(f"[params]\nmail_domain = {example_maildomain}")
     example_config = read_config(inipath)
     assert example_config.max_user_send_per_minute == 60
     assert example_config.filtermail_smtp_port_incoming == 10081
@@ -45,6 +45,8 @@ def test_read_config_basic_using_defaults(tmp_path, maildomain):
     assert example_config.username_min_length == 9
     assert example_config.username_max_length == 9
     assert example_config.password_min_length == 9
+    assert example_config.max_imap_connections == 10000
+    assert example_config.max_smtp_connections == 1000
     assert example_config._unused_keys == []
 
 

chatmaild/src/chatmaild/tests/test_doveauth.py

@@ -19,8 +19,8 @@ def dictproxy(example_config):
     return AuthDictProxy(config=example_config)
 
 
-def test_basic(dictproxy, gencreds):
-    addr, password = gencreds()
+def test_basic(dictproxy, example_gencreds):
+    addr, password = example_gencreds()
     dictproxy.lookup_passdb(addr, password)
     data = dictproxy.lookup_userdb(addr)
     assert data
@@ -107,7 +107,7 @@ def test_handle_dovecot_protocol_user_not_exists(example_config):
     assert wfile.getvalue() == b"N\n"
 
 
-def test_handle_dovecot_protocol_iterate(gencreds, example_config):
+def test_handle_dovecot_protocol_iterate(example_config):
     dictproxy = AuthDictProxy(config=example_config)
     dictproxy.lookup_passdb("asdf00000@chat.example.org", "q9mr3faue")
     dictproxy.lookup_passdb("asdf11111@chat.example.org", "q9mr3faue")
@@ -174,14 +174,14 @@ def test_concurrent_creation_same_account(dictproxy):
     assert len(passwords_seen) == 1
 
 
-def test_50_concurrent_lookups_different_accounts(gencreds, dictproxy):
+def test_50_concurrent_lookups_different_accounts(example_gencreds, dictproxy):
     num_threads = 50
     req_per_thread = 5
     results = queue.Queue()
 
     def lookup():
         for i in range(req_per_thread):
-            addr, password = gencreds()
+            addr, password = example_gencreds()
             try:
                 dictproxy.lookup_passdb(addr, password)
             except Exception:
@@ -202,3 +202,17 @@ def test_50_concurrent_lookups_different_accounts(gencreds, dictproxy):
         res = results.get()
         if res is not None:
             pytest.fail(f"concurrent lookup failed\n{res}")
+
+
+def test_insufficient_resources_block_creation_not_existing_logins(
+    dictproxy, example_gencreds, monkeypatch
+):
+    addr, password = example_gencreds()
+    assert dictproxy.lookup_passdb(addr, password)
+
+    monkeypatch.setattr(
+        chatmaild.doveauth, "has_sufficient_resources", lambda config: False
+    )
+    newaddr, newpassword = example_gencreds()
+    assert not dictproxy.lookup_passdb(newaddr, newpassword)
+    assert dictproxy.lookup_passdb(addr, password)

chatmaild/src/chatmaild/tests/test_metadata.py

@@ -1,4 +1,5 @@
 import io
+import json
 import time
 
 import pytest
@@ -7,6 +8,7 @@ import requests
 from chatmaild.metadata import (
     Metadata,
     MetadataDictProxy,
+    read_appversions,
 )
 from chatmaild.notifier import (
     Notifier,
@@ -369,6 +371,32 @@ def test_iroh_relay(dictproxy):
     assert wfile.getvalue() == b"Ohttps://example.org/\n"
 
 
+def test_read_appversions(tmp_path):
+    path = tmp_path.joinpath("appversions.json")
+    assert read_appversions(path) is None
+
+    path.write_text('{\n  "clients": []\n}')
+    assert read_appversions(path) == '{"clients":[]}'
+
+    # the value travels as a single dict protocol line
+    path.write_text('{"clients": [{"clientId": "one\\ntwo"}]}')
+    assert read_appversions(path) == '{"clients":[{"clientId":"one\\ntwo"}]}'
+
+    path.write_text("bad json")
+    assert read_appversions(path) is None
+
+
+def test_appversions_lookup(dictproxy):
+    # the version information shipped with chatmaild is served as a single line
+    key = b"Lshared/0123/vendor/vendor.dovecot/pvt/server/vendor/deltachat/appversions"
+    key += b"\tuser@example.org"
+    rfile, wfile = io.BytesIO(b"H\n" + key), io.BytesIO()
+    dictproxy.loop_forever(rfile, wfile)
+    value = wfile.getvalue()
+    assert value.startswith(b"O") and value.endswith(b"\n")
+    assert json.loads(value[1:])["clients"]
+
+
 def test_legacy_token_migration(metadata, testaddr):
     with metadata.get_metadata_dict(testaddr).modify() as data:
         data[metadata.DEVICETOKEN_KEY] = ["oldtoken1", "oldtoken2"]

chatmaild/src/chatmaild/tests/test_newmail.py

@@ -48,7 +48,7 @@ def test_create_dclogin_url_ipv4(ipv4_config):
     assert addr in url
 
 
-def test_print_new_account(capsys, monkeypatch, maildomain, tmpdir, example_config):
+def test_print_new_account(capsys, monkeypatch, tmpdir, example_config):
     monkeypatch.setattr(chatmaild.newemail, "CONFIG_PATH", str(example_config._inipath))
     print_new_account()
     out, err = capsys.readouterr()

chatmaild/src/chatmaild/tests/test_syslimits.py

@@ -0,0 +1,45 @@
+import shutil
+
+import psutil
+
+from chatmaild.syslimits import has_sufficient_resources
+
+PERMISSIVE = {
+    "max_load_1m": "99999",
+    "min_available_memory": "0",
+    "min_free_disk_space": "0",
+}
+
+
+def test_rejects_constrained_system(make_config, caplog):
+    assert has_sufficient_resources(make_config("chat.example.org", PERMISSIVE))
+    for settings in (
+        {"max_load_1m": "-1.0"},
+        {"min_available_memory": "99999999G"},
+        {"min_free_disk_space": "99999999G"},
+    ):
+        config = make_config("chat.example.org", PERMISSIVE | settings)
+        caplog.clear()
+        assert not has_sufficient_resources(config), settings
+        assert "registration rejected" in caplog.text
+
+
+def test_unreadable_disk_does_not_reject(make_config, caplog):
+    config = make_config(
+        "chat.example.org", PERMISSIVE | {"min_free_disk_space": "99999999G"}
+    )
+    shutil.rmtree(config.mailboxes_dir)
+    assert has_sufficient_resources(config)
+    assert "ignoring" in caplog.text
+
+
+def test_one_unreadable_value_keeps_other_checks(make_config, monkeypatch, caplog):
+    def raise_error(*args):
+        raise psutil.Error("dud")
+
+    monkeypatch.setattr(psutil, "getloadavg", raise_error)
+    config = make_config(
+        "chat.example.org", PERMISSIVE | {"min_free_disk_space": "99999999G"}
+    )
+    assert not has_sufficient_resources(config)
+    assert "ignoring" in caplog.text

cmdeploy/pyproject.toml

@@ -19,6 +19,7 @@ dependencies = [
   "pytest-xdist", 
   "execnet",
   "imap_tools",
+  "lupa",
   "deltachat-rpc-client",
   "deltachat-rpc-server",
 ]

cmdeploy/src/cmdeploy/acmetool/__init__.py

@@ -4,6 +4,8 @@ from ..basedeploy import Deployer
 
 
 class AcmetoolDeployer(Deployer):
+    bin_path = "/usr/bin/acmetool"
+
     def __init__(self, email, domains):
         self.domains = domains
         self.email = email
@@ -41,8 +43,12 @@ class AcmetoolDeployer(Deployer):
             domains=self.domains,
         )
 
-        self.ensure_systemd_unit("acmetool/acmetool-redirector.service")
-        self.ensure_systemd_unit("acmetool/acmetool-reconcile.service")
+        self.ensure_systemd_unit(
+            "acmetool/acmetool-redirector.service.j2", bin_path=self.bin_path
+        )
+        self.ensure_systemd_unit(
+            "acmetool/acmetool-reconcile.service.j2", bin_path=self.bin_path
+        )
         self.ensure_systemd_unit("acmetool/acmetool-reconcile.timer")
 
     def activate(self):
@@ -52,5 +58,5 @@ class AcmetoolDeployer(Deployer):
 
         server.shell(
             name=f"Reconcile certificates for: {', '.join(self.domains)}",
-            commands=["acmetool --batch --xlog.severity=debug reconcile"],
+            commands=[f"{self.bin_path} --batch --xlog.severity=debug reconcile"],
         )

cmdeploy/src/cmdeploy/acmetool/acmetool-reconcile.service.j2

@@ -4,5 +4,5 @@ After=network.target
 
 [Service]
 Type=oneshot
-ExecStart=/usr/bin/acmetool --batch reconcile
+ExecStart={{ bin_path }} --batch reconcile
 

cmdeploy/src/cmdeploy/acmetool/acmetool-redirector.service.j2

@@ -3,7 +3,7 @@ Description=acmetool HTTP redirector
 
 [Service]
 Type=notify
-ExecStart=/usr/bin/acmetool redirector --service.uid=daemon --bind=127.0.0.1:402
+ExecStart={{ bin_path }} redirector --service.uid=daemon --bind=127.0.0.1:402
 Restart=always
 RestartSec=30
 

cmdeploy/src/cmdeploy/acmetool/response-file.yaml.j2

@@ -1,2 +1,2 @@
 "acme-enter-email": "{{ email }}"
-"acme-agreement:https://letsencrypt.org/documents/LE-SA-v1.7-June-04-2026.pdf": true
+"acme-agreement:https://letsencrypt.org/documents/LE-SA-v1.8-July-06-2026.pdf": true

cmdeploy/src/cmdeploy/basedeploy.py

@@ -51,7 +51,7 @@ def get_resource(arg, pkg=__package__):
     return importlib.resources.files(pkg).joinpath(arg)
 
 
-def configure_remote_units(deployer, mail_domain, units) -> None:
+def configure_remote_units(deployer, mail_domain, units, **kwargs) -> None:
     remote_base_dir = "/usr/local/lib/chatmaild"
     remote_venv_dir = f"{remote_base_dir}/venv"
     remote_chatmail_inipath = f"{remote_base_dir}/chatmail.ini"
@@ -63,6 +63,7 @@ def configure_remote_units(deployer, mail_domain, units) -> None:
             config_path=remote_chatmail_inipath,
             remote_venv_dir=remote_venv_dir,
             mail_domain=mail_domain,
+            **kwargs,
         )
 
         basename = fn if "." in fn else f"{fn}.service"
@@ -226,7 +227,7 @@ class Deployer:
         res = files.directory(name=name, path=path, present=False, **kwargs)
         return self._update_restart_signals(path, res)
 
-    def download_executable(self, url, dest, sha256sum, extract=None):
+    def download_executable(self, url, dest, sha256sum, extract=None, mode="755"):
         existing = host.get_fact(Sha256File, dest)
         if existing == sha256sum:
             return
@@ -243,7 +244,7 @@ class Deployer:
                 f"({dl_cmd}"
                 f" && echo '{sha256sum}  {tmp}' | sha256sum -c"
                 f" && mv {tmp} {dest})",
-                f"chmod 755 {dest}",
+                f"chmod {mode} {dest}",
             ],
         )
         self.need_restart = True

cmdeploy/src/cmdeploy/deployers.py

@@ -33,6 +33,7 @@ from .filtermail.deployer import FiltermailDeployer
 from .mtail.deployer import MtailDeployer
 from .nginx.deployer import NginxDeployer
 from .opendkim.deployer import OpendkimDeployer
+from .pins import IROH_ARTIFACTS, TURN_ARTIFACTS
 from .postfix.deployer import PostfixDeployer
 from .selfsigned.deployer import SelfSignedTlsDeployer
 from .www import build_webpages, find_merge_conflict, get_paths
@@ -138,9 +139,22 @@ class UnboundDeployer(Deployer):
         # On an IPv4-only system, if unbound is started but not configured,
         # it causes subsequent steps to fail to resolve hosts.
         with blocked_service_startup():
+            # dns-root-data is an optional package
+            # that contains /usr/share/dns/root.key
+            #
+            # This file is copied into /var/lib/unbound/root.key
+            # at the start of "unbound" systemd unit
+            # by /usr/libexec/unbound-helper shell script
+            # from the "unbound" package as of version 1.17.1-2+deb12u4
+            #
+            # The same /var/lib/unbound/root.key can be retrieved directly
+            # following the procedure from
+            # <https://www.rfc-editor.org/info/rfc7958/#section-3.1>
+            # with "unbound-anchor -a /var/lib/unbound/root.key"
+            # We don't install and use "unbound-anchor".
             apt.packages(
                 name="Install unbound",
-                packages=["unbound", "unbound-anchor", "dnsutils"],
+                packages=["unbound", "dns-root-data", "dnsutils"],
             )
 
     def configure(self):
@@ -166,12 +180,6 @@ class UnboundDeployer(Deployer):
             dest="/etc/resolv.conf",
             force=True,
         )
-        server.shell(
-            name="Generate root keys for validating DNSSEC",
-            commands=[
-                "unbound-anchor -a /var/lib/unbound/root.key || true",
-            ],
-        )
         self.ensure_directory(
             path="/etc/unbound/unbound.conf.d",
         )
@@ -246,6 +254,13 @@ class LegacyRemoveDeployer(Deployer):
     def install(self):
         apt.packages(name="Remove rspamd", packages="rspamd", present=False)
 
+        # unbound-anchor was used to download /var/lib/unbound/root.key
+        # It is replaced by dns-root-data which contains /usr/share/dns/root.key.
+        # unbound systemd unit copies /usr/share/dns/root.key
+        # into /var/lib/unbound/root.key automatically on start
+        # as long as /usr/share/dns/root.key is present.
+        apt.packages(name="Remove unbound-anchor", packages="unbound-anchor", present=False)
+
         # remove historic expunge script
         # which is now implemented through a systemd timer (chatmail-expire)
         self.remove_file("/etc/cron.d/expunge")
@@ -287,55 +302,48 @@ def check_config(config):
 
 
 class TurnDeployer(Deployer):
+    bin_path = "/usr/local/bin/chatmail-turn"
+
     def __init__(self, mail_domain):
         self.mail_domain = mail_domain
         self.units = ["turnserver"]
 
     def install(self):
-        (url, sha256sum) = {
-            "x86_64": (
-                "https://github.com/chatmail/chatmail-turn/releases/download/v0.4/chatmail-turn-x86_64-linux",
-                "1ec1f5c50122165e858a5a91bcba9037a28aa8cb8b64b8db570aa457c6141a8a",
-            ),
-            "aarch64": (
-                "https://github.com/chatmail/chatmail-turn/releases/download/v0.4/chatmail-turn-aarch64-linux",
-                "0fb3e792419494e21ecad536464929dba706bb2c88884ed8f1788141d26fc756",
-            ),
-        }[host.get_fact(facts.server.Arch)]
-        self.download_executable(url, "/usr/local/bin/chatmail-turn", sha256sum)
+        (url, sha256sum) = TURN_ARTIFACTS[host.get_fact(facts.server.Arch)]
+        self.download_executable(url, self.bin_path, sha256sum)
 
     def configure(self):
-        configure_remote_units(self, self.mail_domain, self.units)
+        configure_remote_units(
+            self, self.mail_domain, self.units, bin_path=self.bin_path
+        )
 
     def activate(self):
         activate_remote_units(self, self.units)
 
 
 class IrohDeployer(Deployer):
+    bin_path = "/usr/local/bin/iroh-relay"
+    config_path = "/etc/iroh-relay.toml"
+
     def __init__(self, enable_iroh_relay):
         self.enable_iroh_relay = enable_iroh_relay
 
     def install(self):
-        (url, sha256sum) = {
-            "x86_64": (
-                "https://github.com/n0-computer/iroh/releases/download/v0.35.0/iroh-relay-v0.35.0-x86_64-unknown-linux-musl.tar.gz",
-                "45c81199dbd70f8c4c30fef7f3b9727ca6e3cea8f2831333eeaf8aa71bf0fac1",
-            ),
-            "aarch64": (
-                "https://github.com/n0-computer/iroh/releases/download/v0.35.0/iroh-relay-v0.35.0-aarch64-unknown-linux-musl.tar.gz",
-                "f8ef27631fac213b3ef668d02acd5b3e215292746a3fc71d90c63115446008b1",
-            ),
-        }[host.get_fact(facts.server.Arch)]
+        (url, sha256sum) = IROH_ARTIFACTS[host.get_fact(facts.server.Arch)]
         self.download_executable(
             url,
-            "/usr/local/bin/iroh-relay",
+            self.bin_path,
             sha256sum,
             extract="gunzip | tar -xf - ./iroh-relay -O",
         )
 
     def configure(self):
-        self.ensure_systemd_unit("iroh-relay.service")
-        self.put_file("iroh-relay.toml", "/etc/iroh-relay.toml")
+        self.ensure_systemd_unit(
+            "iroh-relay.service.j2",
+            bin_path=self.bin_path,
+            config_path=self.config_path,
+        )
+        self.put_file("iroh-relay.toml", self.config_path)
 
     def activate(self):
         self.ensure_service(
@@ -356,6 +364,8 @@ class ChatmailVenvDeployer(Deployer):
     def __init__(self, config):
         self.config = config
         self.units = (
+            # doveauth must restart when chatmaild/ini file changes
+            "doveauth",
             "chatmail-metadata",
             "lastlogin",
             "chatmail-expire",
@@ -504,10 +514,10 @@ def deploy_chatmail(config_path: Path, disable_mail: bool, website_only: bool) -
             ("nginx", 443),
             (["master", "smtpd"], 465),
             (["master", "smtpd"], 587),
-            (["imap-login", "dovecot"], 993),
+            (["dovecot", "imap-login"], 993),
             ("iroh-relay", 3340),
             ("mtail", 3903),
-            ("stats", 3904),
+            (["dovecot", "stats"], 3904),
             ("nginx", 8443),
             (["master", "smtpd"], config.postfix_reinject_port),
             (["master", "smtpd"], config.postfix_reinject_port_incoming),

cmdeploy/src/cmdeploy/dovecot/deployer.py

@@ -14,18 +14,9 @@ from cmdeploy.basedeploy import (
     configure_remote_units,
     is_in_container,
 )
+from cmdeploy.pins import DOVECOT_SHA256, DOVECOT_VERSION
 
-DOVECOT_ARCHIVE_VERSION = "2.3.21+dfsg1-3"
-DOVECOT_PACKAGE_VERSION = f"1:{DOVECOT_ARCHIVE_VERSION}"
-
-DOVECOT_SHA256 = {
-    ("core", "amd64"): "dd060706f52a306fa863d874717210b9fe10536c824afe1790eec247ded5b27d",
-    ("core", "arm64"): "e7548e8a82929722e973629ecc40fcfa886894cef3db88f23535149e7f730dc9",
-    ("imapd", "amd64"): "8d8dc6fc00bbb6cdb25d345844f41ce2f1c53f764b79a838eb2a03103eebfa86",
-    ("imapd", "arm64"): "178fa877ddd5df9930e8308b518f4b07df10e759050725f8217a0c1fb3fd707f",
-    ("lmtpd", "amd64"): "2f69ba5e35363de50962d42cccbfe4ed8495265044e244007d7ccddad77513ab",
-    ("lmtpd", "arm64"): "89f52fb36524f5877a177dff4a713ba771fd3f91f22ed0af7238d495e143b38f",
-}
+DOVECOT_PACKAGE_VERSION = f"1:{DOVECOT_VERSION}"
 
 
 class DovecotDeployer(Deployer):
@@ -34,7 +25,7 @@ class DovecotDeployer(Deployer):
     def __init__(self, config, disable_mail):
         self.config = config
         self.disable_mail = disable_mail
-        self.units = ["doveauth"]
+        self.units = []
 
     def install(self):
         arch = host.get_fact(Arch)
@@ -117,7 +108,7 @@ def _download_dovecot_package(package: str, arch: str) -> tuple[str | None, bool
     if DOVECOT_PACKAGE_VERSION in installed_versions:
         return None, False
 
-    url_version = DOVECOT_ARCHIVE_VERSION.replace("+", "%2B")
+    url_version = DOVECOT_VERSION.replace("+", "%2B")
     deb_base = f"{pkg_name}_{url_version}_{arch}.deb"
     primary_url = f"https://download.delta.chat/dovecot/{deb_base}"
     fallback_url = f"https://github.com/chatmail/dovecot/releases/download/upstream%2F{url_version}/{deb_base}"

cmdeploy/src/cmdeploy/dovecot/dovecot.conf.j2

@@ -37,11 +37,15 @@ default_client_limit = 20000
 # the following warning will be logged:
 #   Warning: service(imap): process_limit (1024) reached, client connections are being dropped
 service imap {
-  process_limit = 50000
+  process_limit = {{ config.max_imap_connections }}
 }
 
-mail_server_admin = mailto:root@{{ config.mail_domain }}
-mail_server_comment = Chatmail server
+{% if config.privacy_mail %}
+# Advertised to clients as IMAP METADATA /shared/admin (RFC 5464).
+# The privacy_mail contact from chatmail.ini is used because it is
+# the only address set by an operator.
+mail_server_admin = mailto:{{ config.privacy_mail }}
+{% endif %}
 
 # `zlib` enables compressing messages stored in the maildir.
 # See

cmdeploy/src/cmdeploy/filtermail/deployer.py

@@ -3,6 +3,7 @@ import os
 from pyinfra import facts, host
 
 from cmdeploy.basedeploy import Deployer
+from cmdeploy.pins import FILTERMAIL_ARTIFACTS
 
 
 class FiltermailDeployer(Deployer):
@@ -20,11 +21,7 @@ class FiltermailDeployer(Deployer):
             return
 
         arch = host.get_fact(facts.server.Arch)
-        url = f"https://github.com/chatmail/filtermail/releases/download/v0.7.1/filtermail-{arch}"
-        sha256sum = {
-            "x86_64": "fc2d8141166f8561b9711fb68c5327fc9421f814c46dc69671a4605a95b175c0",
-            "aarch64": "37e52c5ddb373ef29b5ead89658407c53f48d10ce055a2dbd9c606fa1ebd5f7f",
-        }[arch]
+        url, sha256sum = FILTERMAIL_ARTIFACTS[arch]
         self.download_executable(url, self.bin_path, sha256sum)
 
     def configure(self):

cmdeploy/src/cmdeploy/iroh-relay.service.j2

@@ -2,7 +2,7 @@
 Description=Iroh relay
 
 [Service]
-ExecStart=/usr/local/bin/iroh-relay --config-path /etc/iroh-relay.toml
+ExecStart={{ bin_path }} --config-path {{ config_path }}
 Restart=on-failure
 RestartSec=5s
 User=iroh

cmdeploy/src/cmdeploy/mtail/delivered_mail.mtail

@@ -28,6 +28,13 @@ counter created_nonci_accounts
   }
 }
 
+# doveauth refusing new addresses because a chatmail.ini
+# system resource limit is exceeded.
+counter rejected_registrations
+/registration rejected: / {
+  rejected_registrations++
+}
+
 counter postfix_timeouts
 /timeout after DATA/ {
   postfix_timeouts++
@@ -73,6 +80,11 @@ counter incoming_unencrypted_mail_count
   filtered_incoming_mail_count++
 }
 
+counter incoming_mailer_daemon_mail_count
+/Incoming: Filtering mailer-daemon message from/ {
+  incoming_mailer_daemon_mail_count++
+  filtered_incoming_mail_count++
+}
 
 counter rejected_unencrypted_mail_count
 /Rejected unencrypted mail/ {

cmdeploy/src/cmdeploy/mtail/deployer.py

@@ -1,10 +1,14 @@
 from pyinfra import facts, host
-from pyinfra.operations import apt
+from pyinfra.operations import apt, server
 
 from cmdeploy.basedeploy import Deployer
+from cmdeploy.pins import FILTERMAIL_ARTIFACTS, MTAIL_ARTIFACTS
 
 
 class MtailDeployer(Deployer):
+    bin_path = "/usr/local/bin/mtail"
+    progs_dir = "/etc/mtail"
+
     def __init__(self, mtail_address):
         self.mtail_address = mtail_address
 
@@ -12,19 +16,10 @@ class MtailDeployer(Deployer):
         # Uninstall mtail package to install a static binary.
         apt.packages(name="Uninstall mtail", packages=["mtail"], present=False)
 
-        (url, sha256sum) = {
-            "x86_64": (
-                "https://github.com/google/mtail/releases/download/v3.0.8/mtail_3.0.8_linux_amd64.tar.gz",
-                "d55cb601049c5e61eabab29998dbbcea95d480e5448544f9470337ba2eea882e",
-            ),
-            "aarch64": (
-                "https://github.com/google/mtail/releases/download/v3.0.8/mtail_3.0.8_linux_arm64.tar.gz",
-                "f748db8ad2a1e0b63684d4c8868cf6a373a20f7e6922e5ece601fff0ee00eb1a",
-            ),
-        }[host.get_fact(facts.server.Arch)]
+        (url, sha256sum) = MTAIL_ARTIFACTS[host.get_fact(facts.server.Arch)]
         self.download_executable(
             url,
-            "/usr/local/bin/mtail",
+            self.bin_path,
             sha256sum,
             extract="gunzip | tar -xf - mtail -O",
         )
@@ -36,8 +31,31 @@ class MtailDeployer(Deployer):
             "mtail/mtail.service.j2",
             address=self.mtail_address or "127.0.0.1",
             port=3903,
+            bin_path=self.bin_path,
+            progs_dir=self.progs_dir,
         )
-        self.put_file("mtail/delivered_mail.mtail", "/etc/mtail/delivered_mail.mtail")
+        if self.mtail_address:
+            self.put_file(
+                "mtail/delivered_mail.mtail", f"{self.progs_dir}/delivered_mail.mtail"
+            )
+            url, sha256sum = FILTERMAIL_ARTIFACTS['mtail']
+            self.download_executable(
+                url,
+                f"{self.progs_dir}/filtermail.mtail",
+                sha256sum,
+                mode="644",
+            )
+            if self.need_restart:
+                # Check if all installed mtail rules compile or fail early
+                # --one_shot to exit, --port 0 to not clash with running mtail.
+                server.shell(
+                    name="Validate mtail programs",
+                    commands=[
+                        f"timeout 30 {self.bin_path} --compile_only --one_shot"
+                        f" --progs {self.progs_dir} --logs /dev/null"
+                        " --address 127.0.0.1 --port 0"
+                    ],
+                )
 
     def activate(self):
         active = bool(self.mtail_address)

cmdeploy/src/cmdeploy/mtail/mtail.service.j2

@@ -5,7 +5,7 @@ Wants=network-online.target
 
 [Service]
 Type=simple
-ExecStart=/bin/sh -c "journalctl -f -o short-iso -n 0 | /usr/local/bin/mtail --address={{ address }} --port={{ port }} --progs /etc/mtail --logtostderr --logs -"
+ExecStart=/bin/sh -c "journalctl -f -o short-iso -n 0 | {{ bin_path }} --address={{ address }} --port={{ port }} --progs {{ progs_dir }} --logtostderr --logs -"
 Restart=on-failure
 RestartSec=2s
 

cmdeploy/src/cmdeploy/nginx/nginx.conf.j2

@@ -128,7 +128,10 @@ http {
                         proxy_set_header Connection "upgrade";
                 }
 
-		location /relay/probe {
+		# Endpoints Iroh uses for net_report probes and that clients
+		# probe to tell whether this relay works. Both paths are served
+		# by iroh-relay 0.35 and by the 1.0 line.
+		location /ping {
                         proxy_pass http://127.0.0.1:3340;
                         proxy_http_version 1.1;
 		}

cmdeploy/src/cmdeploy/pins.py

@@ -0,0 +1,62 @@
+"""Versions, hashes, and download URLs for pre-built artifacts fetched during deploy."""
+
+FILTERMAIL_VERSION = "v0.7.4"
+FILTERMAIL_ARTIFACTS = {
+    "x86_64": (
+        f"https://github.com/chatmail/filtermail/releases/download/{FILTERMAIL_VERSION}/filtermail-x86_64",
+        "484cb8dff083134aefba9fce4a6b7ef4784a0f0e28e5108ecf8bb9e58a44fd2c",
+    ),
+    "aarch64": (
+        f"https://github.com/chatmail/filtermail/releases/download/{FILTERMAIL_VERSION}/filtermail-aarch64",
+        "66aa0ca2ca9add7a12d92883d76f8786384092adfde24a3d3a1d0b1f30d23a9e",
+    ),
+    "mtail": (
+        f"https://raw.githubusercontent.com/chatmail/filtermail/{FILTERMAIL_VERSION}/contrib/filtermail.mtail",
+        "948f688bb89ad47e6eb0fc8fa107e201a689f5adc264ff926be487a2a8562b51",
+    ),
+}
+
+MTAIL_VERSION = "3.4.9"
+MTAIL_ARTIFACTS = {
+    "x86_64": (
+        f"https://github.com/jaqx0r/mtail/releases/download/v{MTAIL_VERSION}/mtail_{MTAIL_VERSION}_linux_amd64.tar.gz",
+        "55f64a87f71955bb871c724b4aadf19fe9d854e6327196919c7fe44943427eab",
+    ),
+    "aarch64": (
+        f"https://github.com/jaqx0r/mtail/releases/download/v{MTAIL_VERSION}/mtail_{MTAIL_VERSION}_linux_arm64.tar.gz",
+        "e0a2b66b372ca257d7daeb7ba10f9233a2192a1f9057618fccc6be5c854a2a3c",
+    ),
+}
+
+DOVECOT_VERSION = "2.3.21+dfsg1-3"
+DOVECOT_SHA256 = {
+    ("core", "amd64"): "dd060706f52a306fa863d874717210b9fe10536c824afe1790eec247ded5b27d",
+    ("core", "arm64"): "e7548e8a82929722e973629ecc40fcfa886894cef3db88f23535149e7f730dc9",
+    ("imapd", "amd64"): "8d8dc6fc00bbb6cdb25d345844f41ce2f1c53f764b79a838eb2a03103eebfa86",
+    ("imapd", "arm64"): "178fa877ddd5df9930e8308b518f4b07df10e759050725f8217a0c1fb3fd707f",
+    ("lmtpd", "amd64"): "2f69ba5e35363de50962d42cccbfe4ed8495265044e244007d7ccddad77513ab",
+    ("lmtpd", "arm64"): "89f52fb36524f5877a177dff4a713ba771fd3f91f22ed0af7238d495e143b38f",
+}
+TURN_VERSION = "v0.4"
+TURN_ARTIFACTS = {
+    "x86_64": (
+        f"https://github.com/chatmail/chatmail-turn/releases/download/{TURN_VERSION}/chatmail-turn-x86_64-linux",
+        "1ec1f5c50122165e858a5a91bcba9037a28aa8cb8b64b8db570aa457c6141a8a",
+    ),
+    "aarch64": (
+        f"https://github.com/chatmail/chatmail-turn/releases/download/{TURN_VERSION}/chatmail-turn-aarch64-linux",
+        "0fb3e792419494e21ecad536464929dba706bb2c88884ed8f1788141d26fc756",
+    ),
+}
+
+IROH_VERSION = "v0.35.0"
+IROH_ARTIFACTS = {
+    "x86_64": (
+        f"https://github.com/n0-computer/iroh/releases/download/{IROH_VERSION}/iroh-relay-{IROH_VERSION}-x86_64-unknown-linux-musl.tar.gz",
+        "45c81199dbd70f8c4c30fef7f3b9727ca6e3cea8f2831333eeaf8aa71bf0fac1",
+    ),
+    "aarch64": (
+        f"https://github.com/n0-computer/iroh/releases/download/{IROH_VERSION}/iroh-relay-{IROH_VERSION}-aarch64-unknown-linux-musl.tar.gz",
+        "f8ef27631fac213b3ef668d02acd5b3e215292746a3fc71d90c63115446008b1",
+    ),
+}

cmdeploy/src/cmdeploy/postfix/main.cf.j2

@@ -85,6 +85,14 @@ inet_protocols = all
 
 lmtp_header_checks = regexp:/etc/postfix/lmtp_header_cleanup
 
+# Do not apply header checks to MIME headers
+# and other headers that are actually part of the message body.
+# Reference:
+# <https://www.postfix.org/postconf.5.html#disable_mime_input_processing>
+# <https://www.postfix.org/header_checks.5.html>
+# <https://stump.io/blog/2020/11/29/a-little-gotcha-with-postfixs-header_checks/>
+disable_mime_input_processing = yes
+
 mua_client_restrictions = permit_sasl_authenticated, reject
 mua_sender_restrictions = reject_sender_login_mismatch, permit_sasl_authenticated, reject
 mua_helo_restrictions = permit_mynetworks, reject_invalid_helo_hostname, reject_non_fqdn_helo_hostname, permit

cmdeploy/src/cmdeploy/postfix/master.cf.j2

@@ -18,7 +18,7 @@ smtp      inet  n       -       y       -       -       smtpd
   -o smtpd_tls_mandatory_protocols=>=TLSv1.2
   -o smtpd_proxy_filter=127.0.0.1:{{ config.filtermail_smtp_port_incoming }}
   -o smtpd_relay_restrictions=reject_unauth_destination
-submission inet n       -       y       -       5000    smtpd
+submission inet n       -       y       -       {{ config.max_smtp_connections }}    smtpd
   -o syslog_name=postfix/submission
   -o smtpd_tls_security_level=encrypt
   -o smtpd_tls_mandatory_protocols=>=TLSv1.3
@@ -32,9 +32,9 @@ submission inet n       -       y       -       5000    smtpd
   -o smtpd_sender_restrictions=$mua_sender_restrictions
   -o smtpd_recipient_restrictions=
   -o smtpd_relay_restrictions=permit_sasl_authenticated,reject
-  -o smtpd_client_connection_count_limit=1000
+  -o smtpd_client_connection_count_limit={{ config.max_smtp_connections // 5 }}
   -o smtpd_proxy_filter=127.0.0.1:{{ config.filtermail_smtp_port }}
-smtps     inet  n       -       y       -       5000    smtpd
+smtps     inet  n       -       y       -       {{ config.max_smtp_connections }}    smtpd
   -o syslog_name=postfix/smtps
   -o smtpd_tls_wrappermode=yes
   -o smtpd_tls_security_level=encrypt
@@ -48,7 +48,7 @@ smtps     inet  n       -       y       -       5000    smtpd
   -o smtpd_sender_restrictions=$mua_sender_restrictions
   -o smtpd_recipient_restrictions=
   -o smtpd_relay_restrictions=permit_sasl_authenticated,reject
-  -o smtpd_client_connection_count_limit=1000
+  -o smtpd_client_connection_count_limit={{ config.max_smtp_connections // 5 }}
   -o smtpd_proxy_filter=127.0.0.1:{{ config.filtermail_smtp_port }}
 #628       inet  n       -       y       -       -       qmqpd
 pickup    unix  n       -       y       60      1       pickup
@@ -76,7 +76,6 @@ lmtp      unix  -       -       y       -       -       lmtp
 anvil     unix  -       -       y       -       1       anvil
 scache    unix  -       -       y       -       1       scache
 postlog   unix-dgram n  -       n       -       1       postlogd
-filter    unix -        n       n       -       -       lmtp
 # Local SMTP server for reinjecting outgoing filtered mail.
 127.0.0.1:{{ config.postfix_reinject_port }} inet  n       -       n       -       100      smtpd
   -o syslog_name=postfix/reinject

cmdeploy/src/cmdeploy/service/chatmail-expire.service.f

@@ -5,5 +5,5 @@ After=network.target
 [Service]
 Type=oneshot
 User=vmail
-ExecStart=/usr/local/lib/chatmaild/venv/bin/chatmail-expire /usr/local/lib/chatmaild/chatmail.ini -v --remove
+ExecStart={execpath} {config_path} -v --remove
 

cmdeploy/src/cmdeploy/service/chatmail-fsreport.service.f

@@ -5,5 +5,5 @@ After=network.target
 [Service]
 Type=oneshot
 User=vmail
-ExecStart=/usr/local/lib/chatmaild/venv/bin/chatmail-fsreport /usr/local/lib/chatmaild/chatmail.ini
+ExecStart={execpath} {config_path}
 

cmdeploy/src/cmdeploy/service/turnserver.service.f

@@ -5,7 +5,7 @@ After=network.target
 [Service]
 Type=simple
 Restart=always
-ExecStart=/usr/local/bin/chatmail-turn --realm {mail_domain} --socket /run/chatmail-turn/turn.socket
+ExecStart={bin_path} --realm {mail_domain} --socket /run/chatmail-turn/turn.socket
 
 # Create /run/chatmail-turn
 RuntimeDirectory=chatmail-turn

cmdeploy/src/cmdeploy/tests/conftest.py

@@ -0,0 +1,25 @@
+"""Run the lua scripts we ship under lupa, which bundles Lua 5.4 like dovecot."""
+
+import pytest
+from lupa import lua54
+
+from cmdeploy.basedeploy import get_resource
+
+
+class Lua:
+    """A Lua runtime to load shipped scripts and mocks into."""
+
+    def __init__(self):
+        self.rt = lua54.LuaRuntime(unpack_returned_tuples=True)
+        self.g = self.rt.globals()
+
+    def load(self, path):
+        self.rt.execute(get_resource(path).read_text())
+
+    def table(self, **kwargs):
+        return self.rt.table(**kwargs)
+
+
+@pytest.fixture
+def lua():
+    return Lua()

cmdeploy/src/cmdeploy/tests/online/test_2_deltachat.py

@@ -1,10 +1,12 @@
 import ipaddress
+import json
 import re
 import time
 
 import imap_tools
 import pytest
 import requests
+from chatmaild.tests.test_appversions import check_appversions
 
 from cmdeploy.cmdeploy import get_sshexec
 from cmdeploy.remote import rshell
@@ -51,6 +53,17 @@ class TestMetadataTokens:
         assert res == b"1111 2222"
         assert b"Getmetadata completed" in client.readline()
 
+    def test_get_appversions(self, imap_mailbox):
+        "get app version information shipped with the relay"
+        client = imap_mailbox.client
+        client.send(b'a01 GETMETADATA "" /shared/vendor/deltachat/appversions\n')
+        res = client.readline()
+        assert res[:1] == b"*"
+        res = client.readline().strip().rstrip(b")")
+        # the served value is a single line and passes the shipped file's schema
+        check_appversions(json.loads(res))
+        assert b"Getmetadata completed" in client.readline()
+
 
 class TestEndToEndDeltaChat:
     "Tests that use Delta Chat accounts on the chat mail instance."

cmdeploy/src/cmdeploy/tests/plugin.py

@@ -211,7 +211,7 @@ class ImapConn:
         status, res = self.conn.select()
         if int(res[0]) == 0:
             raise ValueError("no messages in imap folder")
-        status, results = self.conn.fetch("1:*", "(RFC822)")
+        status, results = self.conn.fetch("1:*", "(BODY.PEEK[])")
         assert status == "OK"
         return results
 

cmdeploy/src/cmdeploy/tests/test_dovecot_deployer.py

@@ -111,7 +111,7 @@ def test_download_dovecot_package_uses_archive_version_for_url_and_filename(
 
     deb, changed = dovecot_deployer._download_dovecot_package("core", "amd64")
 
-    archive_version = dovecot_deployer.DOVECOT_ARCHIVE_VERSION.replace("+", "%2B")
+    archive_version = dovecot_deployer.DOVECOT_VERSION.replace("+", "%2B")
     expected_deb = f"/root/dovecot-core_{archive_version}_amd64.deb"
 
     # Verify the returned path uses archive version, not package version (with epoch)

cmdeploy/src/cmdeploy/tests/test_pushlua.py

@@ -0,0 +1,85 @@
+"""Test the push_notification.lua we ship, against a mocked dovecot mail API."""
+
+import textwrap
+
+import pytest
+
+USER1 = "user12345@chat.example.org"
+USER2 = "user67890@chat.example.org"
+
+DOVECOT_MOCKS = textwrap.dedent("""
+    function make_user(username)
+      local function mailbox(_, name)
+        record("mailbox " .. name)
+        return {
+          sync = function() record("sync") end,
+          metadata_set = function(_, k, v)
+            record("metadata_set " .. k .. "=" .. v)
+          end,
+          free = function() record("free") end,
+        }
+      end
+      return {username = username, mailbox = mailbox}
+    end
+""")
+
+
+@pytest.fixture
+def script(lua):
+    lua.rt.execute(DOVECOT_MOCKS)
+    lua.load("dovecot/push_notification.lua")
+    return lua
+
+
+@pytest.fixture
+def deliver(script):
+    def deliver(recipient, sender):
+        calls = []
+        script.g.record = calls.append
+        user = script.g.make_user(recipient)
+        ctx = script.g.dovecot_lua_notify_begin_txn(user)
+        event = script.table(mailbox="INBOX", from_address=sender)
+        script.g.dovecot_lua_notify_event_message_new(ctx, event)
+        script.g.dovecot_lua_notify_end_txn(ctx, True)
+        return calls
+
+    return deliver
+
+
+def test_entry_points_have_the_names_dovecot_calls(script):
+    assert script.g.dovecot_lua_notify_begin_txn is not None
+    assert script.g.dovecot_lua_notify_event_message_new is not None
+    assert script.g.dovecot_lua_notify_end_txn is not None
+
+
+def test_begin_txn_returns_the_user_as_event_context(script):
+    user = script.g.make_user(USER1)
+    ctx = script.g.dovecot_lua_notify_begin_txn(user)
+    ctx.marker = "seen"
+    assert user.marker == "seen"
+
+
+def test_incoming_message_notifies_metadata_server(deliver):
+    assert deliver(USER1, sender=USER2) == [
+        "mailbox INBOX",
+        "sync",
+        "metadata_set /private/messagenew=",
+        "free",
+    ]
+
+
+def test_own_message_does_not_wake_the_sending_device(deliver):
+    assert deliver(USER1, sender=USER1) == [
+        "mailbox INBOX",
+        "sync",
+        "free",
+    ]
+
+
+def test_message_without_from_address_is_notified(deliver):
+    assert deliver(USER1, sender=None) == [
+        "mailbox INBOX",
+        "sync",
+        "metadata_set /private/messagenew=",
+        "free",
+    ]

doc/source/conf.py

@@ -3,6 +3,8 @@
 # For the full list of built-in configuration values, see the documentation:
 # https://www.sphinx-doc.org/en/master/usage/configuration.html
 
+import os
+
 # -- Project information -----------------------------------------------------
 # https://www.sphinx-doc.org/en/master/usage/configuration.html#project-information
 
@@ -16,12 +18,24 @@ author = 'chatmail collective'
 extensions = [
     #'sphinx.ext.autodoc',
     #'sphinx.ext.viewdoc',
+    'sphinx.ext.extlinks',
     'sphinxcontrib.mermaid',
 ]
 
 templates_path = ['_templates']
 exclude_patterns = []
 
+# Repository links go through the roles below.
+# CI sets DOC_GITHUB_REF to the head commit of a pull request,
+gh_ref = os.environ.get("DOC_GITHUB_REF", "main")
+
+extlinks = {
+    "repofile": (f"https://github.com/chatmail/relay/blob/{gh_ref}/%s", "%s"),
+    "repodir": (f"https://github.com/chatmail/relay/tree/{gh_ref}/%s", "%s"),
+}
+
+# Warn about repository links spelled out in full instead of using the roles.
+extlinks_detect_hardcoded_links = True
 
 
 # -- Options for HTML output -------------------------------------------------

doc/source/faq.rst

@@ -54,7 +54,7 @@ How can I upgrade my chatmail relay?
 ------------------------------------
 
 To upgrade to the latest ``main`` branch,
-``cd`` into your local checkout of `https://github.com/chatmail/relay/`_
+``cd`` into your local checkout of https://github.com/chatmail/relay/
 and run the following commands:
 
    ::

doc/source/getting_started.rst

@@ -199,6 +199,93 @@ creating addresses, login with ssh to the deployment machine and run:
 Chatmail address creation will be denied while this file is present.
 
 
+.. _system-limits:
+
+Configurable System Limits
+--------------------------
+
+Limits for auto-rejecting address creation
+..........................................
+
+A relay refuses creation of new addresses
+when the machine runs low on resources,
+but existing addresses keep working.
+
+Three ``chatmail.ini`` settings control this,
+shown here with their defaults::
+
+    max_load_1m = 5
+    min_available_memory = 200M
+    min_free_disk_space = 1G
+
+- ``max_load_1m`` is the maximum 1-minute load average,
+  as reported by ``uptime``;
+  it counts processes waiting for disk I/O as well as for CPU.
+  It is deliberately not scaled by the number of CPUs
+  because I/O rather than CPU is what typically limits a relay.
+
+- ``min_available_memory`` is the minimum memory available without swapping.
+
+- ``min_free_disk_space`` is the minimum free disk space
+  on the file system holding the mailboxes.
+
+The defaults suit the small machine described in
+`Minimal requirements and prerequisites`_.
+
+.. note::
+
+   If you run a bigger machine,
+   raise ``max_load_1m`` after watching ``uptime`` under typical load.
+
+Rejections are logged by the ``doveauth`` service,
+so you can check whether a limit is set too tightly::
+
+    journalctl -u doveauth --grep 'registration rejected'
+
+If ``mtail_address`` is set, rejections are also counted
+in the ``rejected_registrations`` metric.
+
+
+Overall IMAP and SMTP connection limits
+.......................................
+
+Two further settings bound how many connections
+the relay accepts at all, again shown with their defaults::
+
+    max_imap_connections = 10000
+    max_smtp_connections = 1000
+
+``max_imap_connections`` becomes the Dovecot imap process limit,
+and ``max_smtp_connections`` the Postfix process limit
+on each of the submission and smtps ports.
+A single client IP may use up to a fifth of ``max_smtp_connections``.
+Each connection costs memory,
+so these limits defend the relay against running out of RAM.
+
+Unless ``imap_compress`` is enabled,
+an IMAP connection that is idle for ``imap_hibernate_timeout``
+is handed over to the ``imap-hibernate`` process
+and does not count towards ``max_imap_connections``,
+which is why a relay can serve far more IMAP clients
+than this setting suggests.
+
+If you run a large relay with 10k or 100k's of addresses,
+check current connection counts before upgrading
+and set the limits accordingly.
+
+To see how close a running relay is to these two limits,
+copy ``scripts/check-connections.sh`` from the relay repository
+onto the relay and run it there::
+
+    imap             5  ports 143,993   (max_imap_connections)
+                     5  dovecot sessions, 0 of them in an active imap process
+    submission       0  ports 465,587   (max_smtp_connections per port)
+    incoming         0  port 25         (from other relays, no chatmail.ini limit)
+
+It counts established sockets with ``ss``
+and cross-checks the IMAP number against ``doveadm who``.
+
+
 Running a relay with self-signed certificates
 ----------------------------------------------
 

doc/source/overview.rst

@@ -6,13 +6,13 @@ Technical overview
 Directories of the relay repository
 -----------------------------------
 
-The `chatmail relay repository <https://github.com/chatmail/relay/tree/main/>`_
+The `chatmail relay repository <https://github.com/chatmail/relay>`_
 has four main directories.
 
 ``scripts/``
 ~~~~~~~~~~~~~
 
-`scripts <https://github.com/chatmail/relay/tree/main/scripts>`_
+:repodir:`scripts`
 offers two convenience tools for beginners:
 
 - ``initenv.sh`` installs a local virtualenv Python environment and
@@ -71,7 +71,7 @@ The deployed system components of a chatmail relay are:
 ``chatmaild/``
 ~~~~~~~~~~~~~~
 
-`chatmaild <https://github.com/chatmail/relay/tree/main/chatmaild>`_
+:repodir:`chatmaild`
 is a Python package containing several small services which handle
 authentication, trigger push notifications on new messages, ensure
 that outbound mails are encrypted, delete inactive users, and some
@@ -83,25 +83,24 @@ that integrate with Dovecot and Postfix to achieve instant-onboarding
 and only relaying OpenPGP end-to-end messages encrypted messages. A
 short overview of ``chatmaild`` services:
 
--  `doveauth <https://github.com/chatmail/relay/blob/main/chatmaild/src/chatmaild/doveauth.py>`_
+-  :repofile:`doveauth <chatmaild/src/chatmaild/doveauth.py>`
    implements create-on-login address semantics and is used by Dovecot
    during IMAP login and by Postfix during SMTP/SUBMISSION login which
    in turn uses `Dovecot SASL
    <https://doc.dovecot.org/2.3/configuration_manual/authentication/dict/#complete-example-for-authenticating-via-a-unix-socket>`_
    to authenticate logins.
 
--  `chatmail-metadata <https://github.com/chatmail/relay/blob/main/chatmaild/src/chatmaild/metadata.py>`_
-   is contacted by a `Dovecot lua
-   script <https://github.com/chatmail/relay/blob/main/cmdeploy/src/cmdeploy/dovecot/push_notification.lua>`_
-   to store user-specific relay-side config. On new messages, it `passes
-   the user’s push notification
-   token <https://github.com/chatmail/relay/blob/main/chatmaild/src/chatmaild/notifier.py>`_
+-  :repofile:`chatmail-metadata <chatmaild/src/chatmaild/metadata.py>`
+   is contacted by a
+   :repofile:`Dovecot lua script <cmdeploy/src/cmdeploy/dovecot/push_notification.lua>`
+   to store user-specific relay-side config. On new messages, it
+   :repofile:`passes the user’s push notification token <chatmaild/src/chatmaild/notifier.py>`
    to
    `notifications.delta.chat <https://delta.chat/en/help#instant-delivery>`_
    so the push notifications on the user’s phone can be triggered by
    Apple/Google/Huawei.
 
--  `chatmail-expire <https://github.com/chatmail/relay/blob/main/chatmaild/src/chatmaild/expire.py>`_
+-  :repofile:`chatmail-expire <chatmaild/src/chatmaild/expire.py>`
    deletes old messages, large messages, and entire mailboxes
    of users who have not logged in for longer than
    ``delete_inactive_users_after`` days.
@@ -109,15 +108,14 @@ short overview of ``chatmaild`` services:
 -  ``chatmail-quota-expire`` is called by Dovecot's ``quota_warning`` mechanism
    and will automatically remove oldest messages to keep mailboxes well under ``max_mailbox_size``.
 
--  `lastlogin <https://github.com/chatmail/relay/blob/main/chatmaild/src/chatmaild/lastlogin.py>`_
+-  :repofile:`lastlogin <chatmaild/src/chatmaild/lastlogin.py>`
    is contacted by Dovecot when a user logs in and stores the date of
    the login.
 
 ``www/``
 ~~~~~~~~~
 
-`www <https://github.com/chatmail/relay/tree/main/www>`_ contains
-the html, css, and markdown files which make up a chatmail relay’s
+:repodir:`www` contains the html, css, and markdown files which make up a chatmail relay’s
 web page. Edit them before deploying to make your chatmail relay
 stand out.
 
@@ -249,6 +247,33 @@ Fresh chatmail addresses have a mailbox directory that contains:
    directories will typically be empty unless the user of that address
    hasn’t been online for a while.
 
+App version information (experimental)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+A chatmail relay ships the
+:repofile:`appversions.json <chatmaild/src/chatmaild/defaults/appversions.json>`
+file of the ``chatmaild`` package
+and serves its content under the IMAP METADATA key
+``/shared/vendor/deltachat/appversions``.
+Chat apps installed outside of app stores read this key
+to learn about updates and where to download them.
+The mechanism is experimental and may change.
+
+The file travels with the normal deploy:
+update the repository checkout and run ``cmdeploy run``.
+Local modifications of ``appversions.json`` are deployed as-is,
+so you can serve your own app version information,
+including links to app downloads.
+There is no automatic refresh:
+version information changes only when you deploy again.
+
+.. note::
+
+   Note that as of August 2026, only Delta Chat Android Google Play version
+   is beginning to support discovering app versions from relays.
+   Generally, consumers of relay-provided app version information
+   need to verify themselves that downloaded app files are valid.
+
 Active ports
 ~~~~~~~~~~~~
 

doc/source/related.rst

@@ -14,10 +14,11 @@ We know of three work-in-progress alternative implementation efforts:
    it to support all of the features and configuration settings required
    to operate as a chatmail relay.
 
--  `Madmail <https://github.com/themadorg/madmail>`_: an
-   experimental fork of `Maddy Mail Server <https://maddy.email/>`_, modified
-   for chatmail deployments.  It provides a single binary solution
-   for running a chatmail relay.
+-  `Madmail <https://github.com/themadorg/madmail>`_: a Rust-based
+   single-binary chatmail relay.  Madmail v2 is a rewrite of an earlier
+   experimental fork of `Maddy Mail Server <https://maddy.email/>`_.
+   It includes SMTP, IMAP, encryption enforcement, and real-time
+   services (TURN/Iroh), and runs on Linux and Windows.
 
 -  `Chatmail Cookbook <https://github.com/feld/chatmail-cookbook>`_:
    A Chef Cookbook implementing a relay server. The project follows the

scripts/check-connections.sh

@@ -0,0 +1,26 @@
+#!/bin/bash
+#
+# Show current IMAP and SMTP connections on a chatmail relay,
+# to compare against the max_imap_connections and max_smtp_connections
+# settings in chatmail.ini.  Run this on the relay itself.
+set -e
+
+# Count established TCP connections whose local port is one of the arguments.
+established() {
+    filter=$(printf 'sport = :%s or ' "$@")
+    ss -Htn state established "( ${filter% or } )" | wc -l
+}
+
+# doveadm prints a header line and then one line per logged-in user,
+# with that user's number of connections in the second column.
+sessions=$(doveadm who | awk 'NR > 1 { n += $2 } END { print n + 0 }')
+
+# Unless imap_compress is enabled, connections idle for
+# imap_hibernate_timeout are handed over to the imap-hibernate
+# process, so they cost no imap process while idle.
+active=$(pgrep -x imap | wc -l)
+
+printf 'imap        %6d  ports 143,993   (max_imap_connections)\n' "$(established 143 993)"
+printf '            %6d  dovecot sessions, %d of them in an active imap process\n' "$sessions" "$active"
+printf 'submission  %6d  ports 465,587   (max_smtp_connections per port)\n' "$(established 465 587)"
+printf 'incoming    %6d  port 25         (from other relays, no chatmail.ini limit)\n' "$(established 25)"