Email is receiving but not sending

[MTGP]

Hello. I also fail with SMTP.
April hasn’t failed. It fails on the server I installed the day before yesterday.

Virtualmin > System Settings > Server Templates > Default Settings > Mail for domain > Format for usernames that include domain

username@domain：NG
username-domain: OK

I want to use username@domain, but I don’t know how to do it in [?].

The username@domain option is not recommended unless you are migrating users from another system that already uses it. The Postfix mail server has problems with SMTP authentication by users with an @ in the username, and requires that an extra Unix user be created for each mailbox for mail delivery to work.

[Joe]

Please start new topics for new problems. Your question has nothing to do with this topic.

Forum Guidelines: Please read before posting!

In order to maximize our ability to help as many people as possible, and in order to keep things friendly and fun, we have some forum guidelines that we ask you to follow when posting new topics or commenting. I present them below in a delightful series of short “Dos and Don’ts” Do Focus! If you have multiple problems, make multiple posts. Do not combine several problems into one post. Include the following: Distro/version, when you installed, steps to cause the problem, any errors you got, re…

[Adarsh]

Which hosting provider you have? AWS or other

[Joe]

That’s off-topic for this thread. I’m closing it, so no one is tempted to keep going on a wholly unrelated direction. Creating new topics is free.