Yeah, they do. combined.njabl.org has a blacklist of DHCP addresses which is pretty darn complete.
Given the fact most high speed nets are DHCP you could find yourself blocked because the guy before you was a bot.
Not a problem. You use the "smart host" part of sendmail to send all outgoing mail to your ISP's SMTP server.
Except that on an RBL of DHCP I could very well end up the IP that is on the RBL. The effect on people who use legit mail servers on DHCP ranges is the same..