External mail delivery problem

[msshahanshah]

Our scenario
1.web mail server having 150 users
2.local zimbra server with 100 user mailboxes connected over "Dial up"
3.One catch all account on web mail receives mail for the 100 zimbra users.
4.fetch mail connects over IMAP4 and downloads mail from the catch all account.
5. users of webmail can send mail to users on zimbra
6. zimbra users can send mail to any domain using the smart relay of web mail provider

the issue is that the local zimbra users cant send mail to users on web mail.

I forgot to mention both the domain names are the same.
server running Ubuntu 8

I know the postfix looks for users in its address list and when the user is not present it should forward it to another server to try to deliver it.
But how do I configure this?

any help would be appreciated.

By the way this is my first experience with Zimbra.

[phoenix]

It isn't really much use attaching your post to a thread that's already solved and giving it a title of 'almost the same issue', most people will be likely to ignore it. I'll move this to a new thread.

Please update your forum profile with the output of the following command (do not post the output in this thread):

zmcontrol -v

If the mail doesn't go to it's intended recipient what actually happens to it? What errors do you see in the log files when you try to send an email externally? Have you enabled 'use DNS lookup' in the Admin UI so mail gets delivered? Do you have a Split DNS set-up on your system?