diff --git a/mailsrv/assets/postfix/main.cf.part b/mailsrv/assets/postfix/main.cf.part
index f695171..575b134 100644
--- a/mailsrv/assets/postfix/main.cf.part
+++ b/mailsrv/assets/postfix/main.cf.part
@@ -1,3 +1,4 @@
+
 ### Network ###
 # interfaces & protocols to listen on
 inet_interfaces = all
@@ -73,3 +74,5 @@ biff = no
 # See http://www.postfix.org/COMPATIBILITY_README.html -- default to 2 on
 # fresh installs.
 compatibility_level = 2
+# maximum size allowed for sent messages, in bytes
+message_size_limit = 104857600