diff --git a/chatmaild/src/chatmaild/config.py b/chatmaild/src/chatmaild/config.py
index c71e0b27..0fcc494d 100644
--- a/chatmaild/src/chatmaild/config.py
+++ b/chatmaild/src/chatmaild/config.py
@@ -20,6 +20,7 @@ class Config:
         self.mail_domain = params["mail_domain"]
         self.max_user_send_per_minute = int(params["max_user_send_per_minute"])
         self.max_mailbox_size = params["max_mailbox_size"]
+        self.max_message_size = int(params.get("max_message_size", "31457280"))
         self.delete_mails_after = params["delete_mails_after"]
         self.delete_inactive_users_after = int(params["delete_inactive_users_after"])
         self.username_min_length = int(params["username_min_length"])
@@ -73,7 +74,7 @@ def write_initial_config(inipath, mail_domain, overrides):
         new_line = line.strip()
         if new_line and new_line[0] not in "#[":
             name, value = map(str.strip, new_line.split("=", maxsplit=1))
-            value = overrides.pop(name, value)
+            value = extra.pop(name, value)
             new_line = f"{name} = {value}"
         new_lines.append(new_line)
 
diff --git a/chatmaild/src/chatmaild/ini/chatmail.ini.f b/chatmaild/src/chatmaild/ini/chatmail.ini.f
index 1b951356..ab65775e 100644
--- a/chatmaild/src/chatmaild/ini/chatmail.ini.f
+++ b/chatmaild/src/chatmaild/ini/chatmail.ini.f
@@ -17,6 +17,9 @@ max_user_send_per_minute = 60
 # maximum mailbox size of a chatmail address
 max_mailbox_size = 100M
 
+# maximum message size for an e-mail in bytes
+max_message_size = 31457280
+
 # days after which mails are unconditionally deleted
 delete_mails_after = 20
 
diff --git a/chatmaild/src/chatmaild/tests/plugin.py b/chatmaild/src/chatmaild/tests/plugin.py
index ee0baab2..c61fd9b1 100644
--- a/chatmaild/src/chatmaild/tests/plugin.py
+++ b/chatmaild/src/chatmaild/tests/plugin.py
@@ -14,10 +14,11 @@ from chatmaild.config import read_config, write_initial_config
 def make_config(tmp_path):
     inipath = tmp_path.joinpath("chatmail.ini")
 
-    def make_conf(mail_domain):
+    def make_conf(mail_domain, settings=None):
         basedir = tmp_path.joinpath(f"vmail/{mail_domain}")
         basedir.mkdir(parents=True, exist_ok=True)
-        overrides = dict(mailboxes_dir=str(basedir))
+        overrides = settings.copy() if settings else {}
+        overrides["mailboxes_dir"] = str(basedir)
         write_initial_config(inipath, mail_domain, overrides=overrides)
         return read_config(inipath)
 
diff --git a/chatmaild/src/chatmaild/tests/test_config.py b/chatmaild/src/chatmaild/tests/test_config.py
index fa09eda7..2ab96344 100644
--- a/chatmaild/src/chatmaild/tests/test_config.py
+++ b/chatmaild/src/chatmaild/tests/test_config.py
@@ -58,3 +58,8 @@ def test_config_userstate_paths(make_config, tmp_path):
 
     with pytest.raises(ValueError):
         config.get_user(".")
+
+
+def test_config_max_message_size(make_config, tmp_path):
+    config = make_config("something.testrun.org", dict(max_message_size="10000"))
+    assert config.max_message_size == 10000
diff --git a/cmdeploy/src/cmdeploy/dns.py b/cmdeploy/src/cmdeploy/dns.py
index 38e0d9c0..7d2e9c43 100644
--- a/cmdeploy/src/cmdeploy/dns.py
+++ b/cmdeploy/src/cmdeploy/dns.py
@@ -15,7 +15,7 @@ def get_initial_remote_data(sshexec, mail_domain):
 def check_initial_remote_data(remote_data, print=print):
     mail_domain = remote_data["mail_domain"]
     if not remote_data["A"] and not remote_data["AAAA"]:
-        print("Missing A and/or AAAA DNS records for {mail_domain}!")
+        print(f"Missing A and/or AAAA DNS records for {mail_domain}!")
     elif not remote_data["MTA_STS"]:
         print("Missing MTA-STS CNAME record:")
         print(f"mta-sts.{mail_domain}.   CNAME  {mail_domain}")
diff --git a/cmdeploy/src/cmdeploy/postfix/main.cf.j2 b/cmdeploy/src/cmdeploy/postfix/main.cf.j2
index aacf85cf..cfa95cfc 100644
--- a/cmdeploy/src/cmdeploy/postfix/main.cf.j2
+++ b/cmdeploy/src/cmdeploy/postfix/main.cf.j2
@@ -62,8 +62,7 @@ mydestination =
 relayhost = 
 mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
 mailbox_size_limit = 0
-# maximum 30MB sized messages
-message_size_limit = 31457280
+message_size_limit = {{config.max_message_size}}
 recipient_delimiter = +
 inet_interfaces = all
 inet_protocols = all