Another list owner recently told me that he was avoiding activating the web
archive interface on his lists out of fear that if the interface were
active, professional spammers could use it to "mine" for e-mail addresses,
just as they do to capture addresses on usenet groups.

I can understand why someone might set review= private or owner to prevent
this kind of trouble, but I have never heard of a problem stemming from the
archives being available.  I mean, if someone really wanted the addresses
that badly, they could just subscribe to lots of lists and then capture
posters' addresses
as they came through.

Is this a legitimate concern?  If so, how big a one?