Jeff Chan wrote:
"A. Add domains that appear only in spam. Do not add any domains that appear in ham."
As an absolute rule that won't work, because the criminal spammer talks with his rogue registrar in "ham". Don't forget rules #1 spammers lie, and #3 spammers are stupid.
You can't whitelist a domain only because a lying stupid spammer says so. They all have some excuses, that's a part of their business. Bye, Frank