Is there any stated policy against 'shilling'? A suggestion is that you might include it into the rules or code of conduct.
If the term is unfamiliar...
"Shilling" refers to the use of the board's resources, membership list, PM system, etc. to communicate in any form on behalf of a banned member.
Edited by EighteenDelta, : definition of shilling
"I refuse to prove that I exist," says God, "for proof denies faith, and without faith I am nothing."
"But," says Man, "the Babel fish is a dead giveaway isn't it? It could not have evolved by chance. It proves that You exist, and so therefore, by Your own arguments, You don't. Q.E.D."
"Oh dear," says God, "I hadn't thought of that," and promptly vanishes in a puff of logic.
"Oh, that was easy," says Man, and for an encore goes on to prove that black is white and gets himself killed on the next zebra crossing.