AWOL Affiliates

What do you guys do when you can no longer reach an affiliate by email? I have several that never seem to empty their email boxes that send sales and a few that send nothing that I can not contact to help. Do you leave them on the rolls? One in particular is making quite a mess of things and I have no way to contact him other then the snail mail letter I sent. My typical response would be too draconian I imagine so help me out here.

Thanks much

have you tried their whois info?

Naw, I didn't. I will do that for the ones that have sites. I don't think that bloggers with some services like blogger etc, are listed there though:(

do you have a term in your terms and conditions that all affiliates must supply a current email address at all times?