How to add RDNS if I have pointed multiple DNS to the server IP?

Question

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!

Answer 1

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)