Re: Help regarding Postfix and Dovecot SASL

Hello,

I'm currently testing a new setup for my internal mail server with a similar configuration (I'm authenticating users against a Samba4 AD-DC) and I encountered the same error. I was starting to get desperate trying to troubleshoot it.

Am 16.01.2026 um 21:56 schrieb John Fawcett via dovecot:

Maybe this should be

protocol lmtp { auth_username_format = %{user | lower} }

That was the solution! Sometimes it's so simple when you think about it calmly and know where to look.

Thanks, John. You're my hero. And thanks, Christophe, for asking at just the right time. 😉

Best regards, Mike