Although exactly specific to iRedmail, I've found out that any email sent to a .me mac.com apple.com or icloud.com email is being accepted with  status=sent (250 2.5.0 Ok.). Those email never reach the users and never even hit the spam folder of icloud.com or .me etc.

Have you ever met that issue and how do you deal with this ?

==== Required information ====
- iRedMail version (check /etc/iredmail-release):
- Linux/BSD distribution name and version:
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):
- Web server (Apache or Nginx):
- Manage mail accounts with iRedAdmin-Pro?
- Related log if you're reporting an issue:
====