What tools check PTR records?
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You set up your sending IP, configured SPF and DKIM, and emails are still trickling into spam. One thing worth checking is your PTR record. A missing or mismatched PTR is a quiet deliverability killer that's easy to overlook because it lives a layer below the usual authentication checks.
A PTR record (short for pointer record) maps your sending IP address back to a hostname. Receiving mail servers often do a quick reverse DNS check when your email arrives. If there's no PTR record, or if the hostname it returns looks generic or residential, that's a red flag. The real test is FCrDNS validation, which means the IP points to a hostname, and that hostname points back to the same IP. Both directions have to agree.
Tools you can use
Browser-based options are the easiest starting point:
- MXToolbox Reverse Lookup runs the full PTR lookup and checks FCrDNS in one go. Paste your sending IP and you'll see both the reverse and forward results side by side.
- DNS Checker PTR Lookup shows you how the PTR record resolves across different global DNS servers, which is useful if you've recently made changes and want to confirm they've propagated.
Command line works just as well if you're comfortable with a terminal:
dig -x 192.0.2.1That returns your PTR hostname. Then confirm the forward lookup matches:
dig A mail.yourdomain.comIf the IP in that second result matches the IP you started with, FCrDNS passes. If it doesn't, you've got a mismatch to fix.
What good results look like
And a healthy PTR check shows three things. First, a PTR record actually exists for your sending IP (not all IPs have one by default). Second, the hostname is meaningful, something like mail.deepcurrent.io rather than a generic string like 92-12-45-67.static.isp.net. Third, the forward lookup confirms the hostname resolves back to the same IP you started with.
What bad results look like
No PTR record at all is the most common issue, especially if you're on a shared hosting plan or a new dedicated IP. Generic or residential-looking hostnames are another problem. Receiving servers see those and assume you might be a compromised home machine sending spam. A mismatch between your PTR and your forward DNS is the third failure mode, and it means FCrDNS fails entirely.
Don't forget to check every IP you send from, including IPv6 addresses if your setup uses them. It's easy to configure PTR on your primary IPv4 and leave the IPv6 address uncovered.
Still if you're seeing blocklist hits alongside a broken PTR, those two problems are often connected. Our free blocklist checker can confirm whether your IP is listed anywhere while you sort out the PTR side.
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