our Zimbra mail server runs behind a firewall and sends all outgoing mail through our ISPs mail server. The domain name on our Zimbra server is called "mydomain.com" and also the domain of our ISP is called "mydomain.com".
The problem is, that some mail accounts that exist on our ISPs mail server should not exist on our Zimbra server but we need to send mails to these "external" ISP accounts!
Because our local mail domain is also called "mydomain.com" like our ISP's domain the Zimbra server is only looking for "firstname.lastname@example.org" on itself.
How can i setup Zimbra that it looks for mail accounts on itself first and if the mail account "email@example.com" does not exist it should search for it on our ISPs mail server.
Thx for Help!