If using OSSN:
OSSN version: 8.1 premium
Website URL (optional): justbsocial.eu

If facing any bug:
PHP Version : 8.1
Error Log if any: none
Browser: all
OS (Window/Linux/Android/iOS/Mac):

Hello,

I’m running OSSN on a VPS with a configured mailserver.

Sending email directly from the VPS/webmail to a user works fine.

SMTP component in OSSN is enabled and reports as “working.”

External testers (mail-tester.com, etc.) give my domain a perfect score (10/10, 100%).

Emails from the site do reach other addresses/domains, but never Gmail.

Even with MFA component enabled and manual validation done, Gmail does not deliver the messages (not in Inbox, not in Spam).

So it seems the mailserver and DNS (SPF/DKIM/DMARC) are correct, but Gmail rejects or drops OSSN-sent emails.

What am I missing?

Is there an extra configuration step inside OSSN?

Do I need to adjust headers/tags in the SMTP component?

Or is this specifically a Gmail deliverability issue?

Any advice would be greatly appreciated.

Thanks in advance!