Going back to 2005 or so leasing and announcing entire CIDR prefixes was pretty popular for spammers.
A /19 would run you about 8k/m and I assume maxmind updates are included in the cost.
I have no citation for this, but SORBS and friends blacklisted /24 by default. If you had enough servers you could send enough email to turn a profit before your /24 was blacklisted. Only until you got to SORBS level 3 was your prefix blocked. Of course they would delist you for 2000/day.
A /19 would run you about 8k/m and I assume maxmind updates are included in the cost.
I have no citation for this, but SORBS and friends blacklisted /24 by default. If you had enough servers you could send enough email to turn a profit before your /24 was blacklisted. Only until you got to SORBS level 3 was your prefix blocked. Of course they would delist you for 2000/day.