Has anyone's had the issue/behaviour whereby they have received a message from a mailman mailing list and reply to that message, the quoted message in the body of the email doesnt contain the original author in the FROM header.

eg you get:

From: listname@example.com [listname@example.com] On Behalf Of John Doe
Sent: 15 May 2009 12:55
To: someone
Cc: listname@example.com
Subject: something

The TO in the new email is correct and goes to "John Doe". I have not altered my mailman config in anyway. This was not present before i installed the ZCO.

Does anyone know how to restore the previous behaviour.
The Zimbra web interface doesnt do this when it quotes the original message, neither do thunderbird clients connecting via IMAP.