Forum Discussion
tdb2022
Jun 02, 2022Copper Contributor
500 5.3.3 Unrecognized command
Hi all, Our exchange 2016 server start acting up in the last couple days without any configuration changes. I see a few "500 5.3.3 Unrecognized command" in ProtocolLog\SmtpSend. 500 5.3.3 Unreco...
tdb2022
Jun 07, 2022Copper Contributor
I found the problem. It's the GFI MaillEssentials greylist. Don't any error after disable Greylist in Anti-Spam filters.