Rejecting bytes 128-255 as an anti-spam technique is idiotic. If any
noticeable percentage of the Internet started doing this, spammers would
simply stop using those bytes. (Most of them never even started.)
the number of spammers doing this is not a concern. a significant percentage
of spam messages are doing this. and since the messages themselves are
illegally formatted and unlikely to be correctly displayed, it seems perfectly
reasonable to treat them as trash. it's one of the few effective filtering
techniques with zero false positives.