Why won't emails to outside addresses go through?

The POP3 connector deals with incoming email.  Outgoing email is handled by your SMTP connector.  Have you checked it's settings?

are you able to send mail with your internal clients.. try sending mails bia telnet to any external domain.

Quetzal:  What should the settings be?

Npatang:  How do I accomplish that?

Do you know whether email is sent directly to your server from outside sources or does it go through a 3rd party for virus and spam processing first?  You can determine this from the MX record for your domain.  If you are, the test above won't be meaningful.

Do you know whether you use a smarthost for sending email?  If so, you may find some of your outgoing SMTP setting under Connectors->Small Business SMTP Connector.  Otherwise you will find the settings under Servers->your-server-name->Protocols->SMTP->Default SMTP Virtual Server.   You find both of these in Exchange System Manager.

Sorry, the last response should have been a little clearer.  The first paragraph pertains to incoming mail only.  Your issue is with outgoing mail, so the second paragraph is most applicable.

If you do use a smarthost for sending email, then sending email from your server is not a valid test.

Quetzal:  sorry to be dense, but I'll need more assistance.  Say for example that my email domain is "mydomain.com" and addresses are "user@mydomain.com".  What should the SMTP connector's configuration be?