disinformation newsletter suddenly getting flagged as spam by spam assassin. whitelisting it doesn't help.

i'm subscribed to the disinformation mailing list. have been for several
years now. it has only recently started being a problem... i'd say maybe a
month or so ago. someone, and i think it's spamcop, is letting the mailing
list through (probably because i have whitelisted it on webmail), but it's
getting flagged as spam by spam assassin, and when it arrives on my
machine, instead of getting routed to the disinformation mailbox, it gets
routed to the spam mailbox. i'm sure that it's not my mailserver that is
flagging it as spam, because on my mailserver i have a procmail rule that
makes an end run around spam assassin when it encounters a sender address
at disinfo dot com. the only other place that i know of that's filtering
my mail through spam assassin is spamcop.

here's a tracking URL if that will help:
http://www.spamcop.net/sc?id=z730077084zf01b5c5b0e8415125bb1bcee1184e3a7z

i'm at a loss here... hopefully someone can help me out.

thanks
GSDL