You mean exclude hostname that have specific name like "android-7b87234bc987" or "iPhoneNormis"
Or you do not want receive the mail if the iPhone change again the MAC address?
To be more precise, I run Docker on a raspberry PI and it has a bug when restarting containers, as these request IP addresses from DHCP server with a random MAC address, but with static hostname.
The containers have their own static IP addresses already set, so the allocated IP addresses won't ever be used (I scheduled a task to clear this up on a regular basis)
So in short I want to exclude these leases from the email alerts by filtering them out based on hostname.