Hello, I just tried this tutorial and with a bit of configuration, I finally got it to partially work on our servers. Although I could receive emails, it couldn't send anything. Here's the error in the /var/log/mail.log folder: Jun 16 18:25:48 webmail postfix/smtp: CC98E658635: to=<firstname.lastname@example.org>, relay=none, delay=20, delays=0.06/0/20/0, dsn=4.4.3, status=deferred (Host or domain name not found. Name service error for name=gmail.com type=MX: Host not found, try again) Any ideas? Thanks in advance!