==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version  EE 1.7.3
- Deployed with iRedMail Easy or the downloadable installer? No, EE.
- Linux/BSD distribution name and version: Debian Trixie
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): PGSQL
- Web server (Apache or Nginx): NGINX
- Manage mail accounts with iRedAdmin-Pro? No, EE version.
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue. DKIM key is changed with every upgrade.
====

Just a heads up. Every time you upgrade the Enterprise Edition, the DKIM key gets replaced with one that does not honor the DKIM selector one has chosen. One must delete that, then a new key will show up with the DKIM selector, one chosen before the upgrade. Copy and paste that one into the DNS records, and it will match again.

This caught me by surprise on the 1.7.2 update when the postmaster started getting DKIM error domian reports from Google, etc.