Hey I'm a developer of Zimbra and responsible of Nginx-Zimbra Extension. Zimbra have some mail related code to contribute, for example mail SASL authentication, IMAP ID command suport, etc... If u are interested, contact me via jiankuan at zimbra.com. We can talk in more details. Posted at Nginx Forum: http://forum.nginx.org/read.php?2,175271,175271#msg-175271