There is no difference in the installer for Xeams Community and Enterprise Edition. It will run as if you have purchased the Enterprise Edition for the first 30 days. It will then get converted to Community Edition unless a license is purchased.
Maybe you can add new rule like:
ALL: xxxxx@xxxxx
ALL means to check the whole header.
No matter it at at From To CC Received Subject X-Mailer References or any other colon.