Sending mail through a Gmail address via a PHPmailer SMTP script gets flagged as spam
I have a Web form I'm building for some staff members of my online community to use to notify members that their account has been suspended and for how long. No big deal, using html to POST to a PHPmailer script with all of Google's SMTP settings (TLS mode) and the server Gmail account information filled in. It sends fine, but any account other than the backup account for the address (my personal email) receives it in the spam folder.
Now, I can understand if it was getting flagged as spam coming directly from my server, but it's getting flagged after my server is authenticated through Google and sends it through the Gmail address.
Any idea why this is happening and what I can do to fix it? Is it because my IP (or the DO IP range) was flagged for spam from some other user?? Let me know if you need to see any of the scripts or my hosts file or anything, but everything is pretty much default.