How to send webform submission email by SMTP correctly?

I want to send an email to the submitter with SMTP as the default method depends on PHP and always ends up in the spam of both my mail and sender mail. I decided to set SMTP as my default. I installed mailsystem and SMTPauth modules. I set SMTP in malisystem and set my SMTP configuration in STMPauth. However, it never sends correctly. I suppose the problem is with some this in drupal as seen in the log report the error starts from within the system.

https://i.imgur.com/gUWmxSH.png

 

Any ideas to solve this?

Drupal version: 


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