==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 1.6.8
- Deployed with iRedMail Easy or the downloadable installer? Download
- Linux/BSD distribution name and version: Ubuntu 22.04 LTS
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySql
- Web server (Apache or Nginx):Nginx
- Manage mail accounts with iRedAdmin-Pro? Yes
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====
Finally figured out what was causing this on some emails.

reject: RCPT from pyhm-fr4.mta.cloud[62.140.31.35]: 451 4.7.1 <yyy@zzz.com>: Recipient address rejected: Intentional policy rejection, please try again later;

pihole. Soon as a I disable pihole, no issues. Thought I could bypass the pihole by having the dns as 8.8.8.8 instead of using the pihole for the DNS in netplan, where iredmail is running. I've done this for on apple device as pi-hole breaks app download into icloud so this may bypass.

is there somewhere else in iredmail, I need to specify the dns, so it bypasses the pi-hole.