punctuation in subjects

[Jude DaShiell]

Messages with question marks and spaces have been showing up in my inbox 
on another account.  To blacklist these [? ] would take care of those 
characters in a Subject: line.  Would such a regular expression 
effectively blacklist any message having just those two kinds of 
characters in its Subject: line in any combination?  The ultimate 
blacklist entry for such messages would include all punctuation and the 
space character.  These messages are written in fonts not translated by 
us-ascii or unicode, so I'd be open to blacklisting based on national 
origin of messages as well but think both kinds of blacklist entries will 
need to be used in order to shut this traffic off permanently.  The other 
internet service provider runs his system wide open and users have to use 
spamassassin to deal with the consequences.