Enhanced status code Permanent

SMTP error X.5.3

Too many recipients

Updated Jul 1, 2026

The short answer

Too many recipients Common cause: Message contains more recipients than server allows

Quick fix

Split recipients into smaller batches

5 - Permanent. The server will not try again. Fix the cause before you resend.
This code is written X.5.3 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

Split recipients into smaller batches

Related codes

X.5.0 Other or undefined protocol status X.5.1 Invalid command X.5.2 Syntax error X.5.4 Invalid command arguments X.5.5 Wrong protocol version X.5.6 Authentication exchange line too long
All SMTP error codes
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