Enhanced status code Success

SMTP error X.2.3

Message length exceeds mailbox limit

Updated Jul 1, 2026

The short answer

Message length exceeds mailbox limit Common cause: Message is too large for that mailbox

Quick fix

Reduce attachments / message size and resend

2 - Success. Not an error - the server accepted or completed the action.
This code is written X.2.3 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

Reduce attachments / message size and resend

Related codes

X.2.0 Other or undefined mailbox status X.2.1 Mailbox disabled X.2.2 Mailbox full X.2.4 Mailing list expansion problem
All SMTP error codes
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