550.5.7.1 requested action not taken: message refused

[MJSH]

All,

Currently, my company is getting an e-mail that is sent from ouside our
domain and is being rejected. A returned mail sent back to the sender
saying:

550 5.7.1 requested action not taken: message refused
554 5.0.0 service unavailable

The message is a status log file converted into html.

If I take the word Unknown out of the text that is being sent, the
e-mail is accepted.

Does anyone know why?

[Andy David {MVP}]

Post by MJSH
All,
Currently, my company is getting an e-mail that is sent from ouside our
domain and is being rejected. A returned mail sent back to the sender
550 5.7.1 requested action not taken: message refused
554 5.0.0 service unavailable
The message is a status log file converted into html.
If I take the word Unknown out of the text that is being sent, the
e-mail is accepted.
Does anyone know why?

Any content filtering on the SMTP gateways or Exchange Server?