Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I want to host my own (postfix) mailserver for my domain "". For the unlikely event that my server is down, I would like to have receive all mail and forward it to my domain.

Complicating factor is that my ISP does not allow incoming traffic on port 25. So I managed to set-up via Zoneedit that mail from domain 2555 is forwarded to 25 via a separate domain ""

So I set it up in the following way:

  1. I have a forward all mail from to my gmail account
  2. I set up gmail to forward my mail to
  3. Mail from is via a special set-up sent to my server on ip-address w.x.y.z port 2555.
  4. My local firewall makes sure that traffic from port 2555 is forwarded to port 25.

In theory (and partial in practice), this whole chain works. The problem is that some mail is not delivered to my mail server, but other mail is. I can see this in my gmail account because it saves copies of all my mail.

Why is that?

share|improve this question
The problem is that -some- email is delivered and some not. It's about 50%. – Roalt Jan 31 '11 at 12:35

Postfix should tell you why it's rejecting mail. Check /var/log/syslog.

If postfix isn't giving you enough information you can set two variables to increase logging:


The debug_peer_list is a list of IP addresses to debug. You'll want to put Google's addresses here.

The debug_peer_level is the verbosity of logs. This one goes to 9.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.