Recipient address rejected: Domain not found

[Goldy]

Hi everybody.

I am trying to add Proxmox Mail gateway to my organization.

We have an internal mail server (MDaemon).
I have managed to config PMG and relay mails from our mail server out - work great.
But all incoming mails get:
"NOQUEUE: reject: RCPT from mail-vi1eur15on2000.outbound.protection.outlook.com[xx.107.xxx.xx]: 450 4.1.2 <name@domain.com>: Recipient address rejected: Domain not found".
I found some similar threads related to this issue, but none seems to help.

Any help will be appreciate.

Goldy