451 4.7.24: suspicious entries in your SPF record
Gmail found something in the sending domain's SPF record that it considers suspicious, and is rate limiting mail from your IP until it is fixed.
- Gmail
- Provider
- Temporary (4xx)
- Class
- Sources checked
- Author
At a glance
- Code
- 451 4.7.24
- Provider
- Gmail and Google Workspace
- Temporary or permanent
- TemporaryThe sending server keeps the message and tries again later.
- Who has to act
- The sender. The fix is on the sending side: your domain, your server or your list.
- What the server says
451 4.7.24 The SPF record of the sending domain has one or more suspicious entries.
What it means
Gmail read the SPF record of the domain in your envelope sender and judged one or more of its entries suspicious. Google does not publish which entries qualify. The obvious candidates are mechanisms that authorize far more senders than any domain needs: +all, very wide IP ranges, or includes of services you no longer use that pull in large ranges of their own. An SPF record that lets almost anyone pass tells Gmail nothing about who really sent the message. The code is temporary and mail from your IP is rate limited; the permanent form is 550 5.7.24.
Common causes
- An SPF record ending in +all or ?all, which lets any server pass or stay neutral.
- Very broad ranges in ip4 or ip6 mechanisms.
- Includes for services you no longer use, or includes that authorize huge ranges themselves.
How to fix it
- 01Look up your SPF record and list every mechanism and include in it.
- 02Replace +all or ?all with ~all or -all.
- 03Narrow IP ranges to the addresses your servers use, and remove includes for services you have stopped using.
- 04Publish the corrected record, check it with an SPF lookup, and let deferred mail retry.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
- Gmail SMTP errors and codes (Google Workspace Admin Help)knowledge.workspace.google.com
Related codes
- 550 5.7.24Suspicious SPF record, blocked.Gmail rejected the message because the SPF record of the sending domain contains entries that Gmail considers suspicious.
- 451Local error in processing.The receiving server hit a problem on its own side while handling the message and stopped. The reply is temporary, so the sending server will try again.
- 5.7.24SPF check error.The receiving server could not complete the SPF check for the sender's domain, either because of a temporary DNS problem or because the SPF record is broken.
Further reading
All 108 Gmail codesEvery code in the wikiPaste your own bounce