Safari warning for this website

[Ray Proudfoot]

When I click on a link in an email sent from this website Safari is warning This connection is not private. This website may be impersonating www.prepar3dtest.com to steal your personal or financial information.

I didn’t choose the option supplied but logged in via my own saved link. There is a reply to a topic I’m following so the email is genuine. But why does the email say the message was sent from that address? And why doesn’t this forum have a secure https address?