NOTE: You need a SMTP server that accepts TLS or SSL only

1. Specify the full SMTP hostname:port in Email settings, e.g.:smtp.example.com:587
2. Set SMTP security to TLS or SSL (depending on smtp server)
3. Set other fields if necessary
4. Open up /login/forgot_password.php in browser and trigger a password reset email
5. Ensure mail is sent properly.