Set Reverse DNS (PTR)

Forward vs reverse, in one line

An A record maps a domain name to an IP address. A PTR record maps that IP address back to a domain name. Most services never look at the reverse direction, but outbound mail servers check it as a basic anti-spam signal, an IP with no PTR record, or one that does not match the sending domain, is treated as more likely to be spam.

Why this matters specifically if you send mail from a VPS

If you are running your own mail server on a VPS (rather than using cPanel-managed email or a third-party sending service), a missing or mismatched PTR record is one of the most common reasons mail gets rejected or silently dropped by receiving servers, independent of anything about SPF, DKIM or your content.

Setting it

Unlike a regular A record, you cannot set a PTR record yourself in your domain's DNS zone, the IP address block belongs to the hosting provider, so the PTR record has to be set on our side. Open a support ticket with the IP and the hostname you want it to resolve to, this is a quick, routine change.

What to set it to

The PTR record should resolve to a hostname that itself resolves back to the same IP (this is called forward-confirmed reverse DNS, and mail servers specifically check for that match), commonly something like mail.yourdomain.com pointed at both the A record and the PTR.

If outbound mail from a VPS is being rejected and SPF/DKIM both look correct, PTR is the next thing to check, not the last.