==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release):  1.71
- Deployed with iRedMail Easy or the downloadable installer? downloadable installer
- Linux/BSD distribution name and version: RHEL 9
- 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.
====

We have some internal software that can send emails. These emails are sent to an internal mailing list. Today one of those emails was marked as spam. So first question:
1) How do I prevent emails from accounts on our server being marked as spam when being received by other accounts on our server?

More annoyingly, when users here retrieve email using POP3, these emails are not downloaded. I logged onto the webmail interface and I see them in the Junk folder, but they are not downloaded by any of the various email clients that people use here (primarily apple mail and thunderbird). I'm 99% sure this isn't happening on the clients, but on the server. So second question:
2) Where is this happening and how do I turn that off?

I'll also note that in iRedAdmin-Pro, the global spam policy is the default one (and there are no local ones). The checkbox that says "Prefix text [SPAM] to the subject of spam" is NOT checked, but this is happening.

Thanks,

mark