SMTP and general Email delivery/setup

I just trying to setup email delivery via SMTP. So far I had two issues. First I needed to setup openssl_verify_mode to "none". I fixed it equivalent to !152 (merged) . Now I can setup the verify mode in /etc/gitlab/gitlab.rb via gitlab_rails['smtp_openssl_verify_mode'] = "none"

The last thing I'm not sure how to fix/setup, is how to set email_from to a valid email address from my SMTP to prevent the emails to go straight to spam.