I recently had the first need to configure forwarding on an zimbra account and ran into problems with bounces due to SPF checking on the receiving server.
As some research turned out, the sender of the mail resides in a domain that has SPF records, that sender sends the mail to an account on my zimbra server, my server accepts and tries to forward, but the server of the final destination (mx1.gmx.net) does not accept the mail, as my mailserver is not a designated sender for the domain of the sender.
As i can not whitelist my server at gmx.net, i found out that SRS (enveloping) is the proper way to deal with that situation. Is there any way to activate SRS or any other way of rewriting the MAIL FROM in Zimbra or does that mean poking directly with postfix configuration files?
help very much appreciated