I've found a few posts on the subject like, however they are all really old- and don't have working solutions.

Scenario: Employee B replaced employee A and needs to receive employee A's email. Easy enough, but if left to our users to resolve, that will go on forever and we'll have email coming into addresses of people that haven't worked here for a decade. Thus we would like to auto-reply to those old addresses with a canned message stating that this employee is no longer here, and they should direct future messages to employee B, however still forward the message (for a certain time frame anyway).

Problem: As some old posts explain, the auto-reply and the auto-forward in Zimbra seem to clash and they will not work simultaneously.

This seems like such a common circumstance in a business - Does everyone just drop the old address cold and leave senders to figure out what to do?