Thanks Josh!
I think the codes will help me figure out which one I should worry about.
Right now my smartlist is -
Email Suspended Clause contains:
blacklist
banned
rejected
refused
blacklists
blacklisted
whitelist
spamcop
spam
spamslugger
unsolicited
denied
The idea is that it will help me to remove anyone who might have put our IP on blacklist, or reported us as Spam, so we don't email them again.