Reverse DNS (PTR) for Email Sending
A missing or generic PTR record is one of the fastest ways to get filtered by Gmail and Outlook. Here's how reverse DNS works and how to set it right.
TL;DR
Reverse DNS (a PTR record) maps your sending IP back to your hostname. Providers check it — missing or generic rDNS sends you to spam. Set a matching PTR on every sending IP.
Forward vs reverse DNS
Forward DNS maps a hostname to an IP. Reverse DNS (rDNS) does the opposite: it maps an IP back to a hostname via a PTR record. Mail servers use it to sanity-check who's connecting.
Why email needs PTR records
Receivers like Gmail treat IPs with no PTR — or a generic ISP-assigned one like ip-1-2-3-4.host.com — as suspicious. A clean, matching PTR is a baseline trust signal alongside SPF, DKIM and DMARC.
FCrDNS — the gold standard
Forward-Confirmed reverse DNS means your PTR points to a hostname, and that hostname's A record points back to the same IP. Aligning both directions is what providers want to see.
How to set up rDNS
- PTR records are set by whoever owns the IP — usually your host/VPS provider, not your DNS host.
- Open your provider's network/IP panel and set the PTR to your sending hostname (e.g.
mail1.yourdomain.com). - Ensure that hostname has a matching forward A record.
Verify it
Check your PTR with MXToolbox or a reverse-lookup tool. Every IP in your VMTA pool needs one.
AutoPMTA's DNS Health checks rDNS alongside SPF, DKIM and DMARC so nothing is missed. View plans.
Key takeaways
- rDNS maps an IP back to a hostname via a PTR record.
- Missing/generic PTR gets you filtered as spam.
- Aim for forward-confirmed rDNS (FCrDNS).
- Set PTR at your IP owner/host, on every sending IP.
Frequently asked questions
What is a PTR record?+
A PTR (pointer) record is the reverse-DNS entry that maps a sending IP address back to a hostname. Mail servers check it to verify the identity of the connecting server.
Who sets the PTR record?+
PTR records are set by the owner of the IP address — usually your hosting or VPS provider — through their network/IP control panel, not through your domain's DNS host.
What is FCrDNS?+
Forward-Confirmed reverse DNS means the IP's PTR points to a hostname, and that hostname's A record points back to the same IP. This two-way match is the standard mailbox providers expect.