RATS-NoPtr: how to set a PTR record and get your IP delisted

RATS-NoPtr lists IP addresses that have no reverse DNS record. SpamRATS publishes it as a separate zone from RATS-Dyna (generic-looking reverse DNS) and RATS-Spam (volume-based), returning 127.0.0.37 where Dyna returns 127.0.0.36. The absent PTR is what sorts the IP into this zone; the reason it was examined at all is usually connection behaviour, such as floods of connections or repeated invalid-recipient attempts. Publish a PTR and the listing condition goes away, but the behaviour is worth understanding too.

Confirm it in two commands

dig +short 9.113.0.203.all.spamrats.com    # reversed octets; expect 127.0.0.37
dig +short -x 203.0.113.9                  # expect nothing if the PTR is missing

Use the IP from a Received header of real sent mail. If you send through Google Workspace, Microsoft 365, SES, SendGrid, Mailgun or Postmark, the IP belongs to the provider and this is not your listing to fix — your exposure is at the domain level instead.

Setting a PTR, by provider

Reverse DNS lives with whoever owns the IP block. Your domain's DNS zone cannot set it. In practice:

Choose a hostname that looks like a mail server in a domain you own: mail.yourdomain.com, smtp.yourdomain.com, mx1.yourdomain.com. Do not embed the IP in the label and do not use your host's default domain — both shift you from NoPtr into Dyna territory.

Make it forward-confirmed, then match HELO

Three records must agree:

dig +short -x 203.0.113.9        # -> mail.yourdomain.com.
dig +short mail.yourdomain.com   # -> 203.0.113.9

and your SMTP server must announce itself as mail.yourdomain.com in EHLO. Forward-confirmed reverse DNS with a matching banner is an explicit expectation at Gmail, Microsoft and Yahoo for anyone sending from their own IP, so this work pays off well beyond SpamRATS.

Verify from an external resolver, not from the server itself, and allow for cached negative answers before you declare it done.

Delisting

Once dig -x returns your new hostname externally, open the SpamRATS lookup page, check the IP, and submit the removal request. The check is automated, so a request filed while the PTR is still missing will be refused. Dyna and NoPtr listings clear once the reverse DNS condition no longer holds; a simultaneous RATS-Spam listing is a separate matter and needs the sending problem solved first.

If you do not control the IP

Two honest options. Ask the network operator to set the PTR — a reasonable request that any competent host will honour for a mail server. Or stop sending directly from that address and relay through a provider that already has correct reverse DNS and established IP reputation. For low volumes, relaying is usually the better engineering decision even when the PTR is available.

What not to do

• Do not request delisting first and configure later. It wastes the request and some lists penalise repeat attempts.
• Do not point the PTR at a domain you cannot publish an A record for. Without the forward record it is not forward-confirmed and several receivers treat it as no better than missing.
• Do not send mail directly from a dynamic or residential IP. You will be relisted, and Spamhaus PBL will have you as well. Relay instead.
• Do not ignore the behaviour half. NoPtr entries commonly come with connection floods or invalid-recipient hammering. Check your queue for a retry storm, a misconfigured loop, or a compromised account sending through the host.
• Do not expect immediate delivery improvement. The listing clears quickly; receiver-side reputation from whatever caused the attention recovers more slowly.

What a NoPtr listing really tells you

Treat it as a configuration audit rather than an accusation. Every condition behind it — no reverse DNS, a HELO that does not match, direct sending from unprepared space — is independently penalised by the receivers that handle most of your mail. Senders who fix it properly usually find other things improve at the same time.

MailPilot checks sending infrastructure and SPF, DKIM and DMARC alignment, then warms mailboxes at a controlled pace and measures per-provider inbox placement daily, so you can see whether a corrected PTR actually changed where your mail lands.