==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 1.6.0
- Deployed with iRedMail Easy or the downloadable installer? downloadable installer
- Linux/BSD distribution name and version: Debian 11
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):  MySQL
- Web server (Apache or Nginx):   Nginx
- Manage mail accounts with iRedAdmin-Pro?   No
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

I have a new iRedmail installation.   I have the mx record for my domain pointing to a standalone server that scans emails for spam and virus before delivery to iRedmail.  I use this same server with a number of other email servers with no issues.  When it tries to deliver mail to the iRedmail server, the messages are rejected with a " Recipient address rejected: unverified address: Recipient address lookup failed" and a return error 554 5.7.1 Relay access denied.

If I point the mx record direct at the redmail server then messages are properly received and processed.

The spam server is in the same subnet and I have tried using the local and pubic address to connect to iRedmail and placed the public and private ip addresses of the spam server in the mynetwork parameter in opt/iredapd/settings.py and main.cf to no avail.   Is there another parameter I should use to allow message relay?