Enhanced status code

SMTP error X.7.5

Cryptographic failure

Updated Jul 1, 2026

The short answer

Cryptographic failure Common cause: Required key or certificate is unavailable or invalid

Quick fix

Fix certificates, keys, or encryption configuration

This code is written X.7.5 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

Fix certificates, keys, or encryption configuration

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.7.6 Cryptographic algorithm not supported
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