diff --git a/plinth/modules/email/__init__.py b/plinth/modules/email/__init__.py
index 666dee9f4..947f45d63 100644
--- a/plinth/modules/email/__init__.py
+++ b/plinth/modules/email/__init__.py
@@ -53,7 +53,7 @@ class EmailApp(plinth.app.App):
 
     app_id = 'email'
 
-    _version = 3
+    _version = 4
 
     def __init__(self):
         """Initialize the email app."""
diff --git a/plinth/modules/email/privileged/postfix.py b/plinth/modules/email/privileged/postfix.py
index dde893141..fe8aab279 100644
--- a/plinth/modules/email/privileged/postfix.py
+++ b/plinth/modules/email/privileged/postfix.py
@@ -29,7 +29,9 @@ default_config = {
         ','.join([
             'permit_sasl_authenticated',
             'defer_unauth_destination',
-        ])
+        ]),
+    'message_size_limit':
+        '102400000',
 }
 
 submission_options: dict[str, str] = {