Hi!
This is going to be a quick one: As you probably realized, I am one of these Oldtimers that self-host pretty much everything. Including e-mail. And recently, I found a few spammers that made it through my spamfilters by using uncommon TLDs. Blocking individual spammy domains does not work as they seem to have access to a list of ( abandoned ?) 2nd level domains with valid SFP records and they keep on adding new ones. And so I regularly edit my Sendmail Access file to keep them at bay by blocking the entire TLDs.
So far I have blocked:
.sbs
.cfd
.lease
and I will add more as needed.
I have never received any legitimate e-mail from these vanity TLDs and I don’t expect to ever receive one.
Hope this helps,
H.