1

I have hosted 2 email servers in a single server. This server has only one public IP.

I have 2 domain names let say mail.aaa.com and mail.bbb.com which is pointed to this server, let say 1.2.3.4.

My internet service provider would not allow to add multiple RDNS for single IP. So that should I do for this problem?

Thank you!

Yasiru G
  • 6,886
  • 6
  • 23
  • 43

1 Answers1

2

define ONE hostname for your server and put that hostname in the servers SMTP HELO and its RDNS record, also make sure that hostname has an A record to your public ip. it's not important if that hostname is in one of the hosted mail domains, but it can be.

Example:

  • hosted domains: aaa.com, bbb.com
  • server HELO: mail.example.org
  • DNS:
    • mail.example.org A 1.2.3.4
    • 4.3.2.1.in-addr.arpa PTR mail.example.org

(instead of "example.org" you can use one of your hosted domains, eg. HELO/A/rDNS mail.aaa.com)

Gryphius
  • 75,626
  • 6
  • 48
  • 54
  • Thanks a lot Gryphius! I know lot of people has this problem and its better to explain what is the best solution for this. According to your answer emails from mail.aaa.com will work without any issue. What I don't understand is how the mail.bbb.com emails work from this setup? I believe this explanation will help for many people :) – Yasiru G Oct 29 '12 at 02:49
  • 2
    there are two parts of "identification" in a mail transaction. one is "hello, I am server x" (this is the HELO/rDNS/A record part) and the second one is "now I want to send a mail to you, from domain y", x and y do not have to be the same domain. – Gryphius Oct 29 '12 at 05:53