SMTP Error: Could not connect to SMTP host.

I installed WP and using my email ID ( which I created in CP ).
I also generated SSL for mail.domain.com

Installed WP SMTP plugin and trying to use the SMTP setting but email not going.

Any hint?

@CyberPanel @usmannasir Please help.

the smtp plugin should have debug mode or debug log , that should give you some hint.

SMTP
FAILED: 2 - Error with user authentication; Server says: 535 5.7.8 Error: authentication failed: Invalid authentication mechanism

Please show results of //email/testTo: