==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 1.8.4
- Deployed with iRedMail Easy or the downloadable installer?donld
- Linux/BSD distribution name and version: Rocky Linux 10.2
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): Mysql
- Web server (Apache or Nginx):Nginx
- Manage mail accounts with iRedAdmin-Pro? not yet
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====
I found these errors ii /var/log/maillog
Aug  9 01:23:09 xx postfix/postscreen[672494]: warning: btree:/var/lib/postfix/postscreen_cache is unavailable. unsupported dictionary type: btree
Aug  9 01:23:09 xx postfix/postscreen[672494]: warning: btree:/var/lib/postfix/postscreen_cache: cache lookup for '147.1xx.225.xx' failed due to error

This error happens because RHEL 10 distros dont use btree anymore
We also dont have any reference at postfix main.cf to  postscreen_cache_map, then use his default that is the deprecated btree, I sent these commands to fix it

postconf -e "postscreen_cache_map = lmdb:\$data_directory/postscreen_cache"
postconf -e "address_verify_map = lmdb:\$data_directory/verify_cache"

systemctl restart postfix

and after restart:
Aug 14 18:43:24 mx1 postfix/master[183882]: daemon started -- version 3.8.5, configuration /etc/postfix
Aug 14 18:44:30 mx1 postfix/postscreen[183998]: cache lmdb:/var/lib/postfix/postscreen_cache full cleanup: retained=0 dropped=0 entries
Aug 14 18:44:30 mx1 postfix/postscreen[183998]: CONNECT from [109.61.41.176]:44784 to [209.35.184.75]:25
Aug 14 18:44:31 mx1 postfix/dnsblog[183999]: addr 109.61.41.176 listed by domain zen.spamhaus.org as 127.0.0.11
Aug 14 18:44:31 mx1 postfix/dnsblog[183999]: addr 109.61.41.176 listed by domain zen.spamhaus.org as 127.0.0.3
Aug 14 18:44:36 mx1 postfix/postscreen[183998]: DNSBL rank 3 for [109.61.41.176]:44784
Aug 14 18:44:36 mx1 postfix/postscreen[183998]: DISCONNECT [109.61.41.176]:44784

seems working