Gmail sending-IP rejection
Fix Gmail 550 5.7.25 PTR and reverse DNS failure
Gmail returns 550 5.7.25 when the sending IP has no PTR record or the PTR hostname does not resolve forward to that IP. The IP owner must configure reverse DNS.
Gmail reports:
550 5.7.25 The sending IP address doesn't have a PTR record, or the forwarding DNS entry doesn't reference the sending IP address.
550 is permanent for this delivery attempt. Configure correct reverse DNS and send a fresh message.
Manual diagnostic
- Read the actual public sending IP from the Gmail response or sending logs.
- Query its PTR record.
- Resolve the returned hostname with A or AAAA.
- Confirm the original IP appears in the forward result.
- Confirm the hostname is stable and suitable for the mail server's identity.
How to fix it
Ask the VPS, cloud, or connectivity provider that owns the IP to set PTR to a hostname you control. Publish matching forward A/AAAA at that hostname, then verify both directions. Shared email services normally manage this themselves; if their IP fails, open a provider support case rather than editing your domain's ordinary DNS zone.
Frequently asked questions
Who can change a PTR record?
Usually the hosting provider or network owner that controls the sending IP address, not the DNS host for your domain.
What is forward-confirmed reverse DNS?
The IP resolves by PTR to a hostname, and that hostname resolves by A or AAAA back to the same IP.
Does MailFixIt currently test PTR?
No. This page provides manual guidance; the public checker does not yet perform a PTR and forward-confirmation test.
Related email diagnostics
Primary sources: Gmail SMTP errors and codes and Google email sender guidelines.