In news.groups, Brian {Hamilton Kelly} writes:

Why should a "legitimate" user have any need to go via an open proxy?
There is no reason not to go directly to the posting site; using a proxy
is either a vector for mischief, or someone attempting to circumvent his
employer's strictures against use of facilities not approved by policy.

Or someone who doesn't realize that they're running an open proxy. Not
that I have a lot of sympathy, but that's far and away the most common
reason why a block on open proxies would catch people who are not
themselves abusing an open proxy. This isn't an issue with e-mail, since
with e-mail you just tell people to use their ISP's mail server. But with
a place like Google, people *have* to connect directly, and while it would
be great in some abstract sense to have Google helping people clean up
their compromised Windows systems, man, I'd hate to have that support job.
(It may be necessary, mind. It would just also suck a lot.)

There's also the little problem that some of the blacklist operators, er,
lie. Or make, er, strategic alterations for personal reasons. Sure,
there are blacklists that *don't* do this, but I swear, it's getting to
the point where trying to figure out who you can listen to and who you
can't is a full-time job, since it keeps changing. And then people stop
running blacklists by setting the blacklist to reject everyone.

--
Russ Allbery ) http://www.eyrie.org/~eagle/