diff --git a/dms/mailserver.env b/dms/mailserver.env
index 05d6ee3..050b08d 100644
--- a/dms/mailserver.env
+++ b/dms/mailserver.env
@@ -254,7 +254,7 @@ ENABLE_QUOTAS=1
 # Set the message size limit for all users. If set to zero, the size will be unlimited (not recommended!)
 #
 # empty => 10240000 (~10 MB)
-POSTFIX_MESSAGE_SIZE_LIMIT=
+POSTFIX_MESSAGE_SIZE_LIMIT=104857600 # 100MB
 
 # Mails larger than this limit won't be scanned.
 # ClamAV must be enabled (ENABLE_CLAMAV=1) for this.