Hi ,
I've been using zimbra on my company for over a year now ,
I've been using zcs 6.0.0 RC2 for around 5 months , and recently i realized that users can't send emails using zimbra's web interface .
so i thought maybe not using GA is the cause so i've upgraded my installation to ZCS 6.0.4 GA , but i still have this problem
i'm using Ubuntu 8.04.3
it says :

Zimbra
A network service error has occurred
------------------------------------------
method: SendMsgRequest
msg: system failure: Unable to send message
code: service.FAILURE
detail: soap:Receiver
trace: btpool0-8://mail.samexxon.com/service/soap/SendMsgRequest:1263907353312:2faf95412c355e30
.......


any suggestions would be appreciated.