experiment with allowing "Encrypted Subject" which is what K-9 generates in english locale instead of the "..." that Delta Chat and thunderbird use

I installed pyenv and then installed Python 3.9:
$ pyenv install 3.9
$ eval "$(pyenv init -)"
$ pyenv shell 3.9

In a clean repository I ran
$ scripts/cmdeploy init
$ scripts/cmdeploy run
$ scripts/cmdeploy dns
$ scripts/cmdeploy fmt

With the changes made all these commands work.

scripts/cmdeploy test fails some tests
using maildata fixture at
  importlib.resources.files(__package__).joinpath("mail-data")
line but this is not critical.

chatmaild/src/chatmaild/filtermail.py

@@ -17,7 +17,8 @@ def check_encrypted(message):
     """Check that the message is an OpenPGP-encrypted message."""
     if not message.is_multipart():
         return False
-    if message.get("subject") != "...":
+    subject = message.get("subject")
+    if subject not in ("...", "Encrypted Message"):
         return False
     if message.get_content_type() != "multipart/encrypted":
         return False

chatmaild/src/chatmaild/tests/mail-data/encrypted-k9.eml

@@ -0,0 +1,92 @@
+Date: Mon, 05 Feb 2024 12:22:17 +0100
+From: Jus <tqwertyjd@nine.testrun.org>
+To: REDACTED
+User-Agent: K-9 Mail for Android
+Message-ID: <A238D610-1471-4A32-B387-B07811665F6D@nine.testrun.org>
+Autocrypt: addr=tqwertyjd@nine.testrun.org; keydata=
+ mQGNBGWNXoMBDAC+D3Na6zJX8d8NEIIoYqcGsOeJCtPs4DZIE8x4nVIRewwG6+CU0/Su8J1sdNL8
+ InVYnE0DUnRfL9RpT/6oHPsbuN8Yo/xyZbc6Df0MgstrbkiIpIb6YdpMB9vnS9phpTDXuVXwOdb+
+ Q8woi46bZ4jdCm1x/5zW8e2fbahHSSFjDYTKydu3SVTeKPNVdHv9gG7SNQy0emOCP7NXxloi8+aR
+ 4fbgfWpm6yb/pJFDH6jmPZ8LK228qXqSv6urquaCu/yD4S+XR/DvGqj2lA/ntvNhDOjrK4gWt5EA
+ 4djfnTK6z/vt/IkSSca5ITjcbyPBpXnId896NQk76sAdG+K+mJGMJn9YahoI4UvISfCp/B5Fw3Bq
+ 5NmeL5zKN14R5AW5E/Y2J693MJ+VubRoB3VR/RZi5ZeEd1aLkxhqITv6m8FRXrSpC6fIhbqAZGmm
+ 91OAAVNn5/MqaAaWJ5iUKGlNJrDFHVBXEpNah24FEoe6olNiBDNnWJ9tqOmZIiIDPCl8FIEAEQEA
+ AbQadHF3ZXJ0eWpkQG5pbmUudGVzdHJ1bi5vcmeJAbAEEwEKABoECwkIBwIVCgIWAQIZAAWCZY1e
+ gwKeAQKbAwAKCRDtNhlhxu8KoFcjDACfMwEEuEStLsY8Wo/r/mmhZKLjgwRgdcVV7sFpksgk+Myy
+ UyL5VUEi9KVd4lKWNqDSi9S67lW+6hwf/kUrycVIT5AA0i8ZXdtroUpkUIwMOaSEfGpUhPI/kQbz
+ wqYJYES1XPqtpUmL4WR+52CHwtEeKZp+jiKnSNeh1QocBYjld0617dpb6XnAVl+69sQUHioxX7Bu
+ c60CuABcFw78/9hvzX37NC7mvP1vbYS7iEze5p2CUweKtrnnDJpi+oBLAucKQRErIUfJUV/XFdE4
+ j4m+NWAtcnyRVx3WruEWW+fzzb7+fc3fwV8pGCUcD4cb/Bzssg3LVLQiBENRXTmTc5RFxQXWbZae
+ 5f6VLAkVEdoxOMVT2dCjLbwo1nPl9emTTIneRLjLX/cTNdbVZuq/Kv/SoXa05ayljSlZmrCF8k3x
+ zESSeJLrrHkoSPoXECeAJbZyMYmOxZPZChVQhUCxDBAR9wzJmLoHBxoDxYMq16S+Ws4Z+lR2cHj2
+ 4lFAMIzCKsy5AY0EZY1egwEMAIkCo235tKDEUjcW8w77AHFf6+W0183E7US8ze3C8T3UUDsh1nQn
+ h+nZFOnKBRNQHUwRzWgV0ZQmllTrZt67fHOwywqHtaQMe90cZXbvhVoTzehw3B9bYT1j/24LDMy/
+ /eQBZuQeSlcLD6+BC0ro7EGxn5T24CAsmMjrI2ppjgZFlcXo9bA+Xp6rI/HX8AQgWbbegtGnSIDB
+ K20+e+xWANaWUsSBhIwsx2qz0IEq+RER60Zd1xZ41acVyNbDHNocEBnfzOF4GXRAz4M/v9l7ABep
+ 21ALLC/OOKuC8cZDeY+HAbJ0qxggh//+ucpfBF0poOQDJzfNaOGysfn/0NGfxRVbFJc8fNc9P5+K
+ fnjm4RdNkwQRXQeQfqPU9a4AlAH5vl8zHabyYIJUUtP+b7VF6VPfSVzJ+h4BPPIVS/TqKQM6HShX
+ rGs9/DcXfDfcIXxhAfo2M+VKkrlunBev0OrhIDLNn5IigNIa78ZN9cZ/3SZVTfOzFnFuFtnO50tv
+ q5OpvQARAQABiQGfBBgBCgAJBYJljV6DApsMAAoJEO02GWHG7wqgwnQL/ijcTiKNO2Cw4pvgggbL
+ 8e2mgXCQn0aNufbYeylGdX/BP2SMRku5OubjESU0oMVx/Hhy19UkUFhCuOeouSNsbTd6w8Ou+nkh
+ 6bs4KJvhMUFVQe6dE8Reci3EoImcTxV9nqWuvhdXkPddht9Pa5PoRpJlpWxHKpMfrPwWtbW/J8qn
+ dnnc+x9FqxLVY+Z75GbrrMI/I2ClvbfgMnOGQxyZRhcPesiaMyp4bYbX3zxrIZXSG68CQERiMXk8
+ UAeZFPgnm4Hh0rP5cn9enn8tj67ruFsEAU3YMi7eOVOSFlamjH0PTVr3ztdoMathEL7n1s5ksk5b
+ Rgo0SgQy4OgApJIB0B16Zhcd66I4sTZLb2RRkFO9uHDFIOuJGTqYfR3ZjWlEftfxW80g7uLZYwfW
+ gzMOEa9jSZpfWpiWDYfVYcHqQTOAoyc1ndwJno/4pO+kRmYoIUaoBqNqiqNtnTl9eiJHcb8kuaxa
+ PP5Qy9N6C2QONUAb4aFBPe0cYXQ6AUnOqBmd3w==
+Subject: Encrypted Message
+MIME-Version: 1.0
+Content-Transfer-Encoding: 7bit
+Content-Type: multipart/encrypted; boundary="----GAXGEBIG1Q6UA7H3D91DE8MM3Q54OF";
+  protocol="application/pgp-encrypted"
+
+------GAXGEBIG1Q6UA7H3D91DE8MM3Q54OF
+Content-Type: application/pgp-encrypted
+Content-Transfer-Encoding: quoted-printable
+
+Version: 1
+------GAXGEBIG1Q6UA7H3D91DE8MM3Q54OF
+Content-Type: application/octet-stream; name="encrypted.asc"
+Content-Transfer-Encoding: 7bit
+Content-Disposition: inline; filename="encrypted.asc"
+
+-----BEGIN PGP MESSAGE-----
+
+hQGMAzhWohyp3KpBAQwAp76KkR97c29iXj6XwvYIom2c5jx9tNWBKR4t/oz1ltuh
+LR2NUAOxL2dNxBY8AFlFK8G6nWwDt29nOQhmPCSImI/WcG0NqIzZ3Sc+fTbBvnPy
+ne62g686UoE9la7qBSlNo0loQaJOBJ1MnFiVJ8o/p49TV1QoLAxXcaHp9eCs1lDa
+g+wWAxnoCANvPKQLTyDKHC98VBXeiNZuJuXK+yVcLojo/4Bd32py/a2eOKZcQMXs
+DGYZrL5ldphApUlD0R8cNjUA6AfIfwf6kBvN9GgacRFOLUMtP5/7CoYmZJd4ia8o
+8T1WjqlNZtwVcWLRe36Ry9aatavYhjtn5FPr7E/RO9BB0kDYMR5HkaT+WZgDQV1V
+/yaWzPSTP9tuCb4ZWz9St5K2zEcoTKpGbNwmX9YLr0tbcym+nLo6kB8ikD2nN3of
+d5aoDeKutoecMLGIF9pseJAGVkHqKj6FQ/kYYrKDlsA0kqvHuSHj/tI2ANB60TME
+diEy6e+wOn/V+Aq7AImphQGMA+7z+cqPiMawAQv8DtpHdiBdRkW85ZURmEsQQUKy
+6PsMqtRXE/kqU4O1HVyUWsUknDNtbziQDpmcfv1FZzJryLgrHNYbObgsbCgGJ/Ru
+3ahQwOkcHV6lzDZCwYs7QjYLAuw8SvWIISvqYOCHS0x/T0b/kjr3Gl+RJSvt78WW
+YhO0R9z/JagTn+uiHjbmAtN2yJyyk5AfLySZ7gixMkkUlz87AAHVpwopNXdzsJKP
+Qa4Kkc2BUWDCz9JLNEc8U2XmMXLEiXxOBKuvCaDqLnPORP2I7PZnXwyanB8ti10h
+Li3U5R5+/n4TmQwF3e7lbJSpkZAPxBrRNxwASqa5nzm90/SWpYhkZBgWder1vFJA
+rGOK7zOXFYxG6/SsRhftJPW8RC4MM5icK5Au+uUfA3Idosq49tZirjx6t9hdEjDK
+bh1Xj5EbJj78q8LqZhpd3SZD2jFa7TKrfGgtxujEujUtojf/VEcAmwKtxkuP7T12
+OktKIZ3BmeRiUfQVrPUoi/Y/VgBIj9wWQaDuh4QX0sJjAWigCK6gOWqYtWUEjVtL
+PeJB7ZMTTsivKxSS0/uhOap3Ur7nq8vofCY5g60uSAPXsbjIH/ZEAIbS2Stw+pxu
+PzG43YLXuvIOClmQ5iJtjPriUcXAWgf2/Ntcev3pIyuCvKHdrKCDADq871SWUyKj
+1/qmw4YNvGVVfmys1d77KO+TGZeKm5j9XhmJ8WJGw2g8uFKEj9IeZlfPNmhF2dtL
+xVjl/lrJPsZPepzh2MOHh78lHD9zq4voAPog2FXogBiZ4xKWVXPswiqOnHwFe9dn
+yOo3cM6dWKXDhOHWK6a8dF9NQ2Q7RrHlXrXwbfeS7ZQ9llXRa0auPkRQKK0XzdhK
+5otAcu0x65aw40hWOTboJR4AN3ypf8okLLN4fnB1kKaVIdMoWlYdTot3ezt0vy99
+cqpKH6/w6pzxRufezW11bxBFYEPnFzhoblN2VuChPFY2nleiifBS+aaKt2EzF1q5
+iL+dfvJupFXQtKyk8mLBB1QKl/qnBIAJchCeJET4xMpWvAhnluLbT9NO3G1uvN11
+U9ZWi9yhZbYxCubYdVYmI6ZD0NIOxV5kTLdRbWm+Ctz+Lm3I/8bO68J73qqKWbYQ
+rNEhj8QUAmKCdrFGufKp7t7wjgSG+h4/U5Xb+/glPuNgVF110BgbgUaAPGvttQO6
+M+QnelZeb4B525Gj7VYDDVcrEjKDK2kXidxfo8nKN3HFM+eU1cWBJqtJHJXbZ5XZ
+d1pmDypu3O8gOs/re1AVdYdGDou8axCC/yTTwbbbgNFxp88CBUe/Xzoaky4ZKunQ
+Q3rlpD9ayzE7Lp0NvxH90pQWsxDCEkJaADbwcbYtOmvoR1uUAfo2NwWuITG70iFz
+v0lqoiezn7D2J9XutpASQQInJus0gvy0ywjh3XirSoeZ2D4l6XcGMJjz7XNjzfnc
+B4lmHQiGbKsfkPyLdPNkobUHjA2TzyEqxs/tAyMSypo9UwNiGsn2NdMs7oif/xiQ
+X+/e2t5Rm+AJk9U7QYPN8o++px+JDZ+r3PkVAWW4c9rHgzf98Lo6pbt5h4eBrt/X
+MrxVY64iHOwasTdMu9F+fv8+akI=
+=Dj6B
+-----END PGP MESSAGE-----
+
+------GAXGEBIG1Q6UA7H3D91DE8MM3Q54OF--

chatmaild/src/chatmaild/tests/plugin.py

@@ -1,4 +1,6 @@
 import random
+from pathlib import Path
+import os
 import importlib.resources
 import itertools
 from email.parser import BytesParser
@@ -57,7 +59,12 @@ def db(tmpdir):
 
 @pytest.fixture
 def maildata(request):
-    datadir = importlib.resources.files(__package__).joinpath("mail-data")
+    try:
+        datadir = importlib.resources.files(__package__).joinpath("mail-data")
+    except TypeError:
+        # in python3.9 or lower, the above doesn't work, so we get datadir this way:
+        datadir = Path(os.getcwd()).joinpath("chatmaild/src/chatmaild/tests/mail-data")
+
     assert datadir.exists(), datadir
 
     def maildata(name, from_addr, to_addr):

chatmaild/src/chatmaild/tests/test_filtermail.py

@@ -63,6 +63,17 @@ def test_filtermail_encryption_detection(maildata):
     assert not check_encrypted(msg)
 
 
+def test_filtermail_encryption_detection_k9subject(maildata):
+    msg = maildata(
+        "encrypted-k9.eml", from_addr="1@example.org", to_addr="2@example.org"
+    )
+    assert check_encrypted(msg)
+
+    # if the subject is not "..." it is not considered ac-encrypted
+    msg.replace_header("Subject", "Click this link")
+    assert not check_encrypted(msg)
+
+
 def test_filtermail_is_mdn(maildata, gencreds, handler):
     from_addr = gencreds()[0]
     to_addr = gencreds()[0] + ".other"

cmdeploy/src/cmdeploy/__init__.py

@@ -1,6 +1,7 @@
 """
 Chat Mail pyinfra deploy.
 """
+
 import sys
 import importlib.resources
 import subprocess
@@ -303,9 +304,7 @@ def _configure_postfix(config: Config, debug: bool = False) -> bool:
 
     # Login map that 1:1 maps email address to login.
     login_map = files.put(
-        src=importlib.resources.files(__package__).joinpath(
+        src=importlib.resources.files(__package__).joinpath("postfix/login_map"),
-            "postfix/login_map"
-        ),
         dest="/etc/postfix/login_map",
         user="root",
         group="root",

cmdeploy/src/cmdeploy/cmdeploy.py

@@ -2,6 +2,7 @@
 Provides the `cmdeploy` entry point function,
 along with command line option and subcommand parsing.
 """
+
 import argparse
 import shutil
 import subprocess

cmdeploy/src/cmdeploy/dns.py

@@ -5,6 +5,8 @@ import importlib
 import subprocess
 import datetime
 
+from typing import Optional
+
 
 class DNS:
     def __init__(self, out, mail_domain):
@@ -34,7 +36,7 @@ class DNS:
         cmd = "ip a | grep inet6 | grep 'scope global' | sed -e 's#/64 scope global##' | sed -e 's#inet6##'"
         return self.shell(cmd).strip()
 
-    def get(self, typ: str, domain: str) -> str | None:
+    def get(self, typ: str, domain: str) -> Optional[str]:
         """Get a DNS entry"""
         dig_result = self.shell(f"dig -r -q {domain} -t {typ} +short")
         line = dig_result.partition("\n")[0]
@@ -54,22 +56,25 @@ def show_dns(args, out) -> int:
     ssh = f"ssh root@{mail_domain}"
     dns = DNS(out, mail_domain)
 
-    def read_dkim_entries(entry):
-        lines = []
-        for line in entry.split("\n"):
-            if line.startswith(";") or not line.strip():
-                continue
-            line = line.replace("\t", " ")
-            lines.append(line)
-        return "\n".join(lines)
-
     print("Checking your DKIM keys and DNS entries...")
     try:
         acme_account_url = out.shell_output(f"{ssh} -- acmetool account-url")
     except subprocess.CalledProcessError:
         print("Please run `cmdeploy run` first.")
         return 1
-    dkim_entry = read_dkim_entries(out.shell_output(f"{ssh} -- opendkim-genzone -F"))
+
+    dkim_selector = "opendkim"
+    dkim_pubkey = out.shell_output(
+        ssh + f" -- openssl rsa -in /etc/dkimkeys/{dkim_selector}.private"
+        " -pubout 2>/dev/null | awk '/-/{next}{printf(\"%s\",$0)}'"
+    )
+    dkim_entry_value = f"v=DKIM1;k=rsa;p={dkim_pubkey};s=email;t=s"
+    dkim_entry_str = ""
+    while len(dkim_entry_value) >= 255:
+        dkim_entry_str += '"' + dkim_entry_value[:255] + '" '
+        dkim_entry_value = dkim_entry_value[255:]
+    dkim_entry_str += '"' + dkim_entry_value + '"'
+    dkim_entry = f"{dkim_selector}._domainkey.{mail_domain}. TXT {dkim_entry_str}"
 
     ipv6 = dns.get_ipv6()
     reverse_ipv6 = dns.check_ptr_record(ipv6, mail_domain)
@@ -97,7 +102,6 @@ def show_dns(args, out) -> int:
             return 0
         except TypeError:
             pass
-        started_dkim_parsing = False
         for line in zonefile.splitlines():
             line = line.format(
                 acme_account_url=acme_account_url,
@@ -124,28 +128,23 @@ def show_dns(args, out) -> int:
                 current = dns.get("SRV", domain[:-1])
                 if current != f"{prio} {weight} {port} {value}":
                     to_print.append(line)
-            if "  TXT " in line:
+            if " TXT " in line:
                 domain, value = line.split(" TXT ")
                 current = dns.get("TXT", domain.strip()[:-1])
                 if domain.startswith("_mta-sts."):
                     if current:
                         if current.split("id=")[0] == value.split("id=")[0]:
                             continue
-                if current != value:
+
+                # TXT records longer than 255 bytes
+                # are split into multiple <character-string>s.
+                # This typically happens with DKIM record
+                # which contains long RSA key.
+                #
+                # Removing `" "` before comparison
+                # to get back a single string.
+                if current.replace('" "', "") != value.replace('" "', ""):
                     to_print.append(line)
-            if "IN TXT ( " in line:
-                started_dkim_parsing = True
-                dkim_lines = [line]
-            if started_dkim_parsing and line.startswith('"'):
-                dkim_lines.append(" " + line)
-        domain, data = "\n".join(dkim_lines).split(" IN TXT ")
-        current = dns.get("TXT", domain.strip()[:-1])
-        if current:
-            current = "( %s )" % (current.replace('" "', '"\n "'))
-            if current.replace(";", "\\;") != data:
-                to_print.append(dkim_entry)
-        else:
-            to_print.append(dkim_entry)
 
     exit_code = 0
     if to_print:

cmdeploy/src/cmdeploy/dovecot/expunge.cron.j2

@@ -1,10 +1,10 @@
 # delete all mails after {{ config.delete_mails_after }} days, in the Inbox
-2 0 * * * dovecot find /home/vmail/mail/{{ config.mail_domain }} -path '*/cur/*' -mtime +{{ config.delete_mails_after }} -type f -delete
+2 0 * * * vmail find /home/vmail/mail/{{ config.mail_domain }} -path '*/cur/*' -mtime +{{ config.delete_mails_after }} -type f -delete
 # or in any IMAP subfolder
-2 0 * * * dovecot find /home/vmail/mail/{{ config.mail_domain }} -path '*/.*/cur/*' -mtime +{{ config.delete_mails_after }} -type f -delete
+2 0 * * * vmail find /home/vmail/mail/{{ config.mail_domain }} -path '*/.*/cur/*' -mtime +{{ config.delete_mails_after }} -type f -delete
 # even if they are unseen
-2 0 * * * dovecot find /home/vmail/mail/{{ config.mail_domain }} -path '*/new/*' -mtime +{{ config.delete_mails_after }} -type f -delete
+2 0 * * * vmail find /home/vmail/mail/{{ config.mail_domain }} -path '*/new/*' -mtime +{{ config.delete_mails_after }} -type f -delete
-2 0 * * * dovecot find /home/vmail/mail/{{ config.mail_domain }} -path '*/.*/new/*' -mtime +{{ config.delete_mails_after }} -type f -delete
+2 0 * * * vmail find /home/vmail/mail/{{ config.mail_domain }} -path '*/.*/new/*' -mtime +{{ config.delete_mails_after }} -type f -delete
 # or only temporary (but then they shouldn't be around after {{ config.delete_mails_after }} days anyway).
-2 0 * * * dovecot find /home/vmail/mail/{{ config.mail_domain }} -path '*/tmp/*' -mtime +{{ config.delete_mails_after }} -type f -delete
+2 0 * * * vmail find /home/vmail/mail/{{ config.mail_domain }} -path '*/tmp/*' -mtime +{{ config.delete_mails_after }} -type f -delete
-2 0 * * * dovecot find /home/vmail/mail/{{ config.mail_domain }} -path '*/.*/tmp/*' -mtime +{{ config.delete_mails_after }} -type f -delete
+2 0 * * * vmail find /home/vmail/mail/{{ config.mail_domain }} -path '*/.*/tmp/*' -mtime +{{ config.delete_mails_after }} -type f -delete

cmdeploy/src/cmdeploy/tests/online/test_0_login.py

@@ -1,6 +1,7 @@
 import pytest
 import threading
 import queue
+import socket
 
 from chatmaild.config import read_config
 from cmdeploy.cmdeploy import main
@@ -78,3 +79,24 @@ def test_concurrent_logins_same_account(
 
     for _ in conns:
         assert login_results.get()
+
+
+def test_no_vrfy(chatmail_config):
+    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    sock.connect((chatmail_config.mail_domain, 25))
+    banner = sock.recv(1024)
+    print(banner)
+    sock.send(b"VRFY wrongaddress@%s\r\n" % (chatmail_config.mail_domain.encode(),))
+    result = sock.recv(1024)
+    print(result)
+    sock.send(b"VRFY echo@%s\r\n" % (chatmail_config.mail_domain.encode(),))
+    result2 = sock.recv(1024)
+    print(result2)
+    assert result[0:10] == result2[0:10]
+    sock.send(b"VRFY wrongaddress\r\n")
+    result = sock.recv(1024)
+    print(result)
+    sock.send(b"VRFY echo\r\n")
+    result2 = sock.recv(1024)
+    print(result2)
+    assert result[0:10] == result2[0:10] == b"252 2.0.0 "

cmdeploy/src/cmdeploy/tests/online/test_1_basic.py

@@ -83,3 +83,18 @@ def test_exceed_rate_limit(cmsetup, gencreds, maildata, chatmail_config):
             assert b"4.7.1: Too much mail from" in outcome[1]
             return
     pytest.fail("Rate limit was not exceeded")
+
+
+def test_expunged(remote, chatmail_config):
+    outdated_days = int(chatmail_config.delete_mails_after) + 1
+    find_cmds = [
+        f"find /home/vmail/mail/{chatmail_config.mail_domain} -path '*/cur/*' -mtime +{outdated_days} -type f",
+        f"find /home/vmail/mail/{chatmail_config.mail_domain} -path '*/.*/cur/*' -mtime +{outdated_days} -type f",
+        f"find /home/vmail/mail/{chatmail_config.mail_domain} -path '*/new/*' -mtime +{outdated_days} -type f",
+        f"find /home/vmail/mail/{chatmail_config.mail_domain} -path '*/.*/new/*' -mtime +{outdated_days} -type f",
+        f"find /home/vmail/mail/{chatmail_config.mail_domain} -path '*/tmp/*' -mtime +{outdated_days} -type f",
+        f"find /home/vmail/mail/{chatmail_config.mail_domain} -path '*/.*/tmp/*' -mtime +{outdated_days} -type f",
+    ]
+    for cmd in find_cmds:
+        for line in remote.iter_output(cmd):
+            assert not line

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

@@ -142,7 +142,7 @@ def test_echobot(cmfactory, chatmail_config, lp):
     ac = cmfactory.get_online_accounts(1)[0]
 
     lp.sec(f"Send message to echo@{chatmail_config.mail_domain}")
-    chat = ac.create_chat(f'echo@{chatmail_config.mail_domain}')
+    chat = ac.create_chat(f"echo@{chatmail_config.mail_domain}")
     text = "hi, I hope you text me back"
     chat.send_text(text)
     lp.sec("Wait for reply from echobot")