spam in gmail

Did you setup SPF, DKIM and DMARC for your domain?
 
Is there any useful information in the mail headers? Not sure if there is a way to show all email headers from the Gmail Web-UI, maybe you need a proper email client for that.
Some spam filters might add some headers that tell you the spam score - that might give you a clue what is happening.
 

About

The Proxmox community has been around for many years and offers help and support for Proxmox VE, Proxmox Backup Server, and Proxmox Mail Gateway.
We think our community is one of the best thanks to people like you!

Get your subscription!

The Proxmox team works very hard to make sure you are running the best software and getting stable updates and security enhancements, as well as quick enterprise support. Tens of thousands of happy customers have a Proxmox subscription. Get yours easily in our online shop.

Buy now!