==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
  RedMail version (check /etc/iredmail-release): .9.9
- Deployed with iRedMail Easy or the downloadable installer? NO
- Linux/BSD distribution name and version: Debian 9
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):  MySQL
- Web server (Apache or Nginx): Ngnix
- Manage mail accounts with iRedAdmin-Pro? No
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

Tried to search for relevant topic with no luck.  I am noticing many if not most of my spam has  mismatch domains between sender and reply to.  Often they will use a burner gmail domain to spray spam and a hotmail or corporate domain for reply to. How can I make a rule to reject all email with a domain mismatch.  I will deal with legitimate mismatches as they occur but doubt it will be a wide spread problem.    Thanks