Due to the fact that we do not know exactly what you changed, maybe this post can help you: https://talk.plesk.com/threads/email-err...ed.306524/
There are a couple solutions to try
Just in case that doesn't help, you are not alone: Google: roundcube smtp error (250) authentication failed
a lot of people have gotten this issue.
There are a couple solutions to try
Just in case that doesn't help, you are not alone: Google: roundcube smtp error (250) authentication failed
a lot of people have gotten this issue.