Enhanced status code

SMTP error X.7.23

SPF validation failed

Updated Jul 1, 2026

The short answer

SPF validation failed Common cause: SPF returned fail

Quick fix

Correct the SPF record and authorized sending sources

This code is written X.7.23 because the reason is the same whether the failure is temporary (a 4 first digit) or permanent (a 5). Read the first digit of your own bounce to know which applies.

How to fix it

Correct the SPF record and authorized sending sources

Related codes

X.7.0 Other or undefined security status X.7.1 Delivery not authorized X.7.2 Mailing list expansion prohibited X.7.3 Security conversion required but impossible X.7.4 Security features not supported X.7.5 Cryptographic failure
All SMTP error codes
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