Here's how my email arrives:

I've attempted using the PHPMailer library since a year ago, but each time I failed, and could not figure out the reasons why this happens even after asking my web hosting service. Could anyone shed some light on what I should do to really authenticate the emails from my domain?

I've read the Google/Gmail docs, set the SPF records correctly, and my web host has DKIM set by default. I've also done multiple other settings (during the year which I can't remember) but Nothing removed that big red question mark...I'm trying to send emails professionally for my new business and I know people would be turned away by the warning.

Please assist.