Enhanced status code

SMTP error X.6.4

Conversion with loss performed

Updated Jul 1, 2026

The short answer

Conversion with loss performed Common cause: Message delivered after conversion lost some data

Quick fix

Usually no fix needed unless the loss is unacceptable

This code is written X.6.4 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

Usually no fix needed unless the loss is unacceptable

Related codes

X.6.0 Other or undefined media error X.6.1 Media not supported X.6.2 Conversion required and prohibited X.6.3 Conversion required but unsupported X.6.5 Conversion failed X.6.6 Message content not available
All SMTP error codes
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