News: Redirect Filter Change
Redirect filters configured via sieve (Roundcube > Settings > Filters) are known for being reasonably dumb objects, meaning they do as configured and little to nothing more. As a result, redirect filters cause a common problem in which filters configured to Redirect will allow you to send out an email claiming to be From the sender of the email you received. In more explicit terms, you are spoofing a third-party sender. Spoofing a third-party sender is especially problematic when you receive an email from "firstname.lastname@example.org" and then send out an email claiming to be from "email@example.com," which is an address you do not own or control.
Today we have deployed a change to this logic. As of today, redirect filters will rewrite envelope senders to be you, the recipient. This change means that you will be the one sending the email. You will no longer be spoofing the address of the person who sent the email to you.
While forwarders (as configured in DirectAdmin) remain the recommended option for forwarding email, we will no longer be interested in preventing users from configuring Redirect filters that send out to third-party mail services, as we have done in the past.