"this is probably a FAQ, but is it possible to filter out
 unsubscribe messages (i.e. prevent them from beeing sent
 to the list)?"
 
You would need software capable of examining the body of a message, as well
as, optionally, the header, and making a very basic decision - is this person
asking to unsubscribe ?
 
This software would have to make the decision correctly, more often than a
human did, before it could be regarded as an improvement. This is a very
tricky task ... even humans can't parse each others' sentences and come up
with the same meaning every time, never mind software.
 
A more conventional approach is to use separate addresses, one for control
messages, IE, subscribe/unsubscribe/modify-subscription ... and the other for
messages pertaining to the topic for which the mailing list exists. However,
asd you may have noticed, humans can't even discriminate between these two,
simple, addresses. To expect humans to write software capable of parsing the
range of possible administrative requests is to open oneself to disappointment,
IMHO.
 
So, no, until you get humans to 100% correctly use mail aliases, you will
still see an occasional administrative message. Unless you want to be the
filtering mechanism ...
 
-- richard
 
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