fix: only allow ports above 1024 for imap + smtp

Default behavior is processing headers
that are actually part of the message body.
This is unlikely to be needed
as headers such as Received are not added into MIME parts,
but may result in broken DKIM signatures
if the body is modified.

.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/v0.7.0/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

README.md

@@ -8,7 +8,12 @@ Chatmail relay servers are interoperable Mail Transport Agents (MTAs) designed f
 -  **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.

chatmaild/pyproject.toml

@@ -9,8 +9,7 @@ dependencies = [
   "iniconfig",
   "filelock",
   "requests",
-  "crypt-r >= 3.13.1 ; python_version >= '3.11'",
-  "domain-validator",
+  "crypt-r >= 3.13.1 ; python_version >= '3.13'",
 ]
 
 [tool.setuptools]

chatmaild/src/chatmaild/config.py

@@ -1,8 +1,8 @@
 import ipaddress
 from pathlib import Path
+from random import randint
 
 import iniconfig
-from domain_validator import DomainValidator
 
 from chatmaild.user import User
 
@@ -25,7 +25,6 @@ class Config:
             self.mail_domain = f"[{raw_domain}]"
             self.postfix_myhostname = ipaddress.IPv4Address(raw_domain).reverse_pointer
         else:
-            DomainValidator().validate_domain_re(raw_domain)
             self.ipv4_relay = None
             self.mail_domain = raw_domain
             self.postfix_myhostname = raw_domain
@@ -43,6 +42,11 @@ class Config:
         self.username_max_length = int(params.pop("username_max_length", 9))
         self.password_min_length = int(params.pop("password_min_length", 9))
         self.www_folder = params.pop("www_folder", "")
+
+        self.imap_port = int(params.pop("imap_port", 143))
+        self.imaps_port = int(params.pop("imaps_port", 993))
+        self.smtp_port = int(params.pop("smtp_port", 587))
+        self.smtps_port = int(params.pop("smtps_port", 465))
         self.filtermail_smtp_port = int(params.pop("filtermail_smtp_port", "10080"))
         self.filtermail_smtp_port_incoming = int(
             params.pop("filtermail_smtp_port_incoming", "10081")
@@ -140,8 +144,15 @@ def parse_size_mb(limit):
 
 def write_initial_config(inipath, mail_domain, overrides):
     """Write out default config file, using the specified config value overrides."""
-    content = get_default_config_content(mail_domain, **overrides)
-    inipath.write_text(content)
+    content = get_default_config_content(mail_domain, **overrides).splitlines()
+    used_ports = [25, 53, 80, 143, 402, 443, 465, 587, 993, 3340, 3903, 3904, 8443, 10080, 10081, 10082, 10083, 10025, 10026]
+    for config_key in ["smtp_port", "imap_port", "smtps_port", "imaps_port"]:
+        value = randint(1024, 65536)
+        while value in used_ports:
+            value = randint(65535)
+        used_ports.append(value)
+        content.append(f"{config_key} = {value}")
+    inipath.write_text("\n".join(content))
 
 
 def get_default_config_content(mail_domain, **overrides):

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

@@ -1,2 +1,2 @@
 "acme-enter-email": "{{ email }}"
-"acme-agreement:https://letsencrypt.org/documents/LE-SA-v1.6-August-18-2025.pdf": true
+"acme-agreement:https://letsencrypt.org/documents/LE-SA-v1.8-July-06-2026.pdf": true

cmdeploy/src/cmdeploy/basedeploy.py

@@ -166,7 +166,7 @@ class Deployer:
             return self.put_template(src, dest, **kwargs)
         return self.put_file(src, dest)
 
-    def put_file(self, src, dest, mode="644"):
+    def put_file(self, src, dest, mode="644", **kwargs):
         if isinstance(src, str):
             src = get_resource(src)
         res = files.put(
@@ -176,6 +176,7 @@ class Deployer:
             user="root",
             group="root",
             mode=mode,
+            **kwargs,
         )
 
         return self._update_restart_signals(dest, res)

cmdeploy/src/cmdeploy/deployers.py

@@ -164,6 +164,7 @@ class UnboundDeployer(Deployer):
         self.put_file(
             src=BytesIO(b"nameserver 127.0.0.1\nnameserver 9.9.9.9\n"),
             dest="/etc/resolv.conf",
+            force=True,
         )
         server.shell(
             name="Generate root keys for validating DNSSEC",
@@ -495,15 +496,15 @@ def deploy_chatmail(config_path: Path, disable_mail: bool, website_only: bool) -
         if config.tls_cert_mode == "acme":
             port_services.append(("acmetool", 402))
         port_services += [
-            (["imap-login", "dovecot"], 143),
+            (["imap-login", "dovecot", "nginx"], config.imap_port),
             # acmetool previously listened on port 80,
             # so don't complain during upgrade that moved it to port 402
             # and gave the port to nginx.
             (["acmetool", "nginx"], 80),
             ("nginx", 443),
-            (["master", "smtpd"], 465),
-            (["master", "smtpd"], 587),
-            (["imap-login", "dovecot"], 993),
+            (["master", "smtpd", "nginx"], config.smtp_port),
+            (["master", "smtpd", "nginx"], config.smtps_port),
+            (["imap-login", "dovecot", "nginx"], config.imaps_port),
             ("iroh-relay", 3340),
             ("mtail", 3903),
             ("stats", 3904),

cmdeploy/src/cmdeploy/filtermail/deployer.py

@@ -20,10 +20,10 @@ class FiltermailDeployer(Deployer):
             return
 
         arch = host.get_fact(facts.server.Arch)
-        url = f"https://github.com/chatmail/filtermail/releases/download/v0.7.0/filtermail-{arch}"
+        url = f"https://github.com/chatmail/filtermail/releases/download/v0.7.4/filtermail-{arch}"
         sha256sum = {
-            "x86_64": "451f295a85b3b12dbb0f89e18ec319f742ee46dec218f20f7923bfb017a248bd",
-            "aarch64": "6833061b2a2028264fdeb32f0a6123e1ff73de57dace125364016300b748452e",
+            "x86_64": "484cb8dff083134aefba9fce4a6b7ef4784a0f0e28e5108ecf8bb9e58a44fd2c",
+            "aarch64": "66aa0ca2ca9add7a12d92883d76f8786384092adfde24a3d3a1d0b1f30d23a9e",
         }[arch]
         self.download_executable(url, self.bin_path, sha256sum)
 

cmdeploy/src/cmdeploy/mtail/delivered_mail.mtail

@@ -73,6 +73,11 @@ 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/nginx/autoconfig.xml.j2

@@ -7,14 +7,14 @@
     <displayShortName>{{ config.mail_domain }}</displayShortName>
     <incomingServer type="imap">
       <hostname>{{ config.mail_domain }}</hostname>
-      <port>993</port>
+      <port>{{ config.imaps_port }}</port>
       <socketType>SSL</socketType>
       <authentication>password-cleartext</authentication>
       <username>%EMAILADDRESS%</username>
     </incomingServer>
     <incomingServer type="imap">
       <hostname>{{ config.mail_domain }}</hostname>
-      <port>143</port>
+      <port>{{ config.imap_port }}</port>
       <socketType>STARTTLS</socketType>
       <authentication>password-cleartext</authentication>
       <username>%EMAILADDRESS%</username>
@@ -28,14 +28,14 @@
     </incomingServer>
     <outgoingServer type="smtp">
       <hostname>{{ config.mail_domain }}</hostname>
-      <port>465</port>
+      <port>{{ config.smtps_port }}</port>
       <socketType>SSL</socketType>
       <authentication>password-cleartext</authentication>
       <username>%EMAILADDRESS%</username>
     </outgoingServer>
     <outgoingServer type="smtp">
       <hostname>{{ config.mail_domain }}</hostname>
-      <port>587</port>
+      <port>{{ config.smtp_port }}</port>
       <socketType>STARTTLS</socketType>
       <authentication>password-cleartext</authentication>
       <username>%EMAILADDRESS%</username>

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

@@ -31,6 +31,26 @@ stream {
             ~\bimap\b 127.0.0.1:993;
         }
 
+        server {
+                listen {{ config.smtp_port }};
+                proxy_pass 127.0.0.1:587;
+        }
+
+        server {
+                listen {{ config.imap_port }};
+                proxy_pass 127.0.0.1:143;
+        }
+
+        server {
+                listen {{ config.smtps_port }};
+                proxy_pass 127.0.0.1:465;
+        }
+
+        server {
+                listen {{ config.imaps_port }};
+                proxy_pass 127.0.0.1:993;
+        }
+
         server {
                 listen 443;
                 {% if not disable_ipv6 %}

cmdeploy/src/cmdeploy/postfix/lmtp_header_cleanup

@@ -1,23 +1,3 @@
-# List of headers for incoming messages 
-# that must be retained for functionality and compatibility reasons 
-/^From:/            DUNNO
-/^Message-Id:/      DUNNO
-/^Chat-/            DUNNO
-/^Content-Type:/    DUNNO
-
-# For receiving clear-text messages (still supported in May 2026)
-/^Subject:/         DUNNO
-/^Date:/            DUNNO
-/^To:/              DUNNO
-/^CC:/              DUNNO
-/^References:/      DUNNO
-/^In-Reply-To:/     DUNNO
-
-# Senders might support Autocrypt 1 but not RFC9788 (Header Protection) 
-/^Autocrypt:/       DUNNO
-
-# SecureJoin V2 protocol headers (for backward compatibility) 
-/^Secure-Join/      DUNNO
-
-# Ignore all other headers
-/.*/                IGNORE
+/^DKIM-Signature:/            IGNORE
+/^Authentication-Results:/            IGNORE
+/^Received:/            IGNORE

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/tests/plugin.py

@@ -10,13 +10,11 @@ from pathlib import Path
 
 import pytest
 from chatmaild.config import is_valid_ipv4, read_config
-from domain_validator import DomainValidator
 
 
 def format_mail_domain(raw_domain: str) -> str:
     if is_valid_ipv4(raw_domain):
         return f"[{raw_domain}]"
-    DomainValidator().validate_domain_re(raw_domain)
     return raw_domain
 
 

doc/source/overview.rst

@@ -225,21 +225,6 @@ Accepting and delivering mail
         nginx -.SMTP inet:465.-> smtpd-smtps
         mta2[Remote relay] -.SMTP inet:25.-> smtpd-smtp
         mta2 -.HTTPS /mxdeliv.-> nginx
-        style postfix fill:#363
-        style qmgr fill:#252
-        style authclean fill:#252
-        style cleanup fill:#252
-        style lmtp-filtermail fill:#252
-        style lmtp fill:#252
-        style bounce fill:#252
-        style smtpd-submission fill:#252
-        style smtpd-smtps fill:#252
-        style smtpd-reinject-outgoing fill:#252
-        style smtpd-reinject-incoming fill:#252
-        style smtpd-smtp fill:#252
-        style filtermail-outgoing fill:#225
-        style filtermail-incoming fill:#225
-        style filtermail-transport fill:#225
 
 Operational details of a chatmail relay
 ----------------------------------------