A PTR record - also called reverse DNS or rDNS - maps your mail server's IP address back to its hostname. It is the reverse of a normal A record, and receiving mail servers check it to confirm your server is legitimate. A missing or mismatched PTR is a frequent cause of mail being rejected or filtered.
This is the key point that trips people up: the PTR record is controlled by whoever owns the IP address - your hosting provider - not by your domain's DNS. You cannot set it in your normal DNS zone. You request it from the provider (or set it in the provider's control panel if they expose that).
The PTR should resolve to the hostname your mail server announces in its HELO/EHLO greeting, for example mail.yourdomain.com. For a fully valid setup you need forward-confirmed reverse DNS, which means three things agree:
IP address -> PTR -> mail.yourdomain.com mail.yourdomain.com -> A record -> the same IP address
When the forward A record and the reverse PTR match, receivers treat your server as properly configured.
Provide your provider with the sending IP and the desired hostname (for example mail.yourdomain.com), and make sure that hostname already has an A record pointing to that IP. The provider adds the PTR to the reverse zone for the IP.
Once set, confirm it from any machine:
dig -x your-server-ip +short # should return mail.yourdomain.com
Then confirm the forward record matches:
dig mail.yourdomain.com +short # should return your-server-ip
If the two agree, your reverse DNS is correct and one common deliverability barrier is removed.
On a SoftSys managed VPS we set the PTR record on your sending IP to match your mail hostname as part of email setup, so your server passes reverse-DNS checks from the start.
