Basic SMTP reply code · RFC 5321
454 Temporary failure (TLS or authentication)
TLS is not available right now (RFC 3207), or authentication failed because of a temporary server problem (RFC 4954); it is not a wrong password.
- Class: 4yz · Temporary failure
4yz: a transient failure. The command was not accepted, but may succeed if repeated; the sending server should try again (RFC 5321 §4.2.1).
How 454 appears at providers
The exact text from the provider's documentation, as you see it in the bounce, and what it means.
Gmail
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454 4.7.0
Too many login attempts, please try again later.
Too many login attempts on the account; wait before trying again.
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454 4.7.0
Cannot authenticate due to a temporary system problem. Try again later.
Authentication fails because of a temporary problem at Google; try again later.
Have the whole error message?
Sources: RFC 5321 · RFC 3463 · RFC 3464 · IANA · Gmail · Microsoft 365 · read on 26 September 2026