My zimbra server's postfix has myhostname=mailserver1.holtecnet.local
Zimbra has 2 domains holtecnet.local & We are using zimbra to receive mails for When user sends a mail, it is actually relayed to another postfix server which further sends mail. I want to stop use of this external postfix server by stopping relay of mails and let zimbra send the mail.
So far so good. It works. But problem comes when a mail is received for which account do not exist on zimbra. This mail should be dropped, but it is placed in deferred queue. Perhaps zimbra thinks that some other server is also handling domain and hence account may exists there.

Can solution to this problem be setting ?
As server is in production, I wanted to confirm this on forums before actually trying up .