Alma Linux 8 emails not sending

Hi,
On two different vps with both AlmaLinux8 and CWP panel, two different provider as well, but the same issue. Email are not being sent, they stay in the queue.
Postfix and Dovecot running properly, sDNS/PTR set and validated, so all looks ok, but the smtp not working. Firewall is ok too. Anybody experienced anything like this?

Have you tested the server by sending an email from the CLI using s-nail?

My most recent install of CWP lives on AlmaLinux behind NAT and works perfectly.

If your emails are not not being dispatched verify that PTR record matches the hostname of the machine. Also make sure that port 25 locally and remotely in both directions are reachable. Firewall is also a common issue.

I'm guessing since he hasn't replied since June 2024 he got it figured out.