I noticed that Zimbra for some (if not all) our accounts, when sending emails, replaces From and Return-Path headers with account alias. For instance if we have a user called Joe Doe (joe.doe@example.org) with an alias joe@example.org all emails sent by him are delivered with headers From: joe@example.org.

How can I prevent it from happening?

We are using Zimbra Network Edition 7.1.1