Hey, guys!
I'm migrating from a postfix server to a zimbra server, but I will not be able to migrate everything in just one weekend, because there are many accounts, more than 600, so I would need that when zimbra received the message, it pass the message to the postfix server, only if the account does not already exist in zimbra, because I do not want users to lose any email or customers receive the response that the account does not exist.
Does anyone know any solutions? I own MailScanner.