mails from domains on my server to domains on my server

Hi,
I've upgraded from sqwebmail 3.2.0 to 4.0.1. And users can not send e-mail from domain on my server to other domain on my server or the same domain on my server through webmail. But outgoing mails from domains on my server to outside through webmail goes. Or by using any e-mail client like outlook express, messages from domain on my server to other domain on my server or the same domain on my server goes too.

Is this  problem sqwebmail related? 

After upgrade webmail users can noıt change their passwords through webmail. One of sqwebmail mailing list users said it is vpomail related problem. I use vpopmail 5.0. Is this problem related vpopmail too?  Is there an adaptation problem between sqwebmil 4.0.1 and vpopmail 5.0? Must I upgrade to vpopmail 5.2?

Thanks... 

Özgür ÖZASLAN
http://ozaslan.ifbim.itu.edu.tr