Problem using email plugin

Hello, I have Wordpress installed on a server and it has the WP Mail SMTP plugin.

And I have a problem with the SMTP Host configuration.

I put mail.domain.com

The message that appears: SMTP Error: Could not connect to SMTP host.

I did a research says that it is a mistake in aaPanel.
can anybody help me?

aaP_fabioanesio
have you checked that your smtp server is working?

Yes, it works normal