IskyI
ZITADEL•2w ago•
4 replies
Isky

Trouble configuring SMTP in Zitadel with Mailcow Postfix

I’m currently testing Zitadel to replace my old, unstable auth server. I want it to send noreply emails to users, similar to how my previous auth server worked. My Mailcow setup doesn’t have an actual noreply user and it only relays emails from addresses it doesn’t host.

I’ve set up Zitadel and Mailcow on a Docker network. Zitadel is configured to send mail to Mailcow’s Postfix container at mailcowdockerized-postfix-mailcow-1:25 using Zitadel’s “Generic SMTP” provider. Postfix does receive something from Zitadel, but fails to understand it:

warning: non-SMTP command from zitadel-zitadel-1.mailcow_postfix[10.99.0.3]: *


Meanwhile, Zitadel reports a failure to authenticate:

RpcError(INTERNAL): could not add smtp auth, check if both your user and password are correct, if they're correct maybe your provider requires an auth method not supported by ZITADEL (EMAIL-s9kfs)


I’m assuming this is because Zitadel is trying to speak SMTP in a way Postfix doesn’t understand when connecting directly on port 25. My old auth server worked fine with this same Postfix setup.

Has anyone successfully configured Zitadel to send mail via a Mailcow Postfix relay without an actual user, or can anyone suggest how to make Zitadel and Postfix speak the same SMTP language over a Docker network?

Thanks!
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