ResolutionEvery Internet-reachable host should have a name.
The consequences of this are becoming more and more obvious.
Many services available on the Internet will not talk to you if you
aren't correctly registered in the DNS and mail is one of them.
It is strongly recommended that your mail server have configured
reverse DNS zone (PTR record) as many mail servers will not
accept mail from mail servers with no reverse DNS entry.
It's should look similar to this:
More detailed information about how to configurea PTR record is avalible at
Also please note that it's not enough to configure correct PTR record in your DNS system.
Related data should be added in to ISP (RIPE) database, you should refer to your ISP team
for help and advsced assistance.
Also often range of IP's provided by ISP has already configured some default reverse
DNS records, then you can ask to change them.