Currently I have an issue with the sender distribution list.

The scenario are as below:

The Sender:
The Recipient:

Distribution List:
User List in

The end-user in domain is using MDaemon, when the mail drop to one of the account in Zimbra, MDaemon will download the mail from Zimbra.

The Main problem is, when the email sent by the user in the sender domain ( to the email address ( The email will received by the Zimbra with same message ID.

I already set the zimbraMessageIdDedupeCacheSize to "0", but it still treat it as same message id. When I looked at the mail drop box, only one single email is there.

When the MDaemon download the email from zimbra, it treat it as a bad mail.

Please help to advice, what should I do.
Thank you in advanced!