How to restore a backup?

Your software
My Mautic version is:V3
My PHP version is: 7.3.27
My Database type and version is:

Your problem
My problem is: I Have an Own mail server. I think this authentication Problem But don’t know how to authenticate on my server.

These errors are showing in the log:

Failed to authenticate on SMTP server with username “” using 1 possible authenticators. Authenticator PLAIN returned Expected response code 250 but got an empty response

Steps I have tried to fix the problem: