I have the latest version 3.0 and I've rectified the issue of mail not sending to gmails and others.
This is what I did.. I navigated to Notification settings -> Global Templates -> Emails sent from and I changed the mail from "
[email protected]" to my site email but it was bringing 403 error so I disabled mod security in my cpanel and changed the email (
[email protected] to my site email) in my database. There is a table called "general settings' and it fixed the issue of 403 and email sending to gmails.