On Sun, 16 Nov 2003, David Laight wrote:

> > Just my $.25: I could not e-mail my friend, just because the administrator
> > blindly banned all *.tpnet.pl hosts. I don't feel responsible for the fact,
> > that some percent (large? small?) of tpnet.pl users are spammers and script
> > kiddies. I've tried to e-mail that sysadmin, but unfortunatley (yes, you
> > guessed it) his e-mail was also "protected" too.

> It is also worth noting that the ISPs mail servers tend to get
> blacklisted if any of their clients has (or appears to have had)
> an open relay.  So you are likely to block a lot of wanted mail.

Some of the early, now-defunct, DNSBL's were abused in the same
fashion as Usenet cancels, and gave the whole DNSBL thing a black eye.
All the lists recommended on openrbl.org today have clear and open
removal guidelines, and a clear and definite policy on who gets on it
in the first place.

Some of the best ones (spamcop, abuseat) auto-expire every entry after
a few hours. If your netblock is blocked by one of those, it's not a
value judgement about your choice of ISP; it means someone is spamming
NOW, and the tide must be stemmed NOW. It's all very dynamic. ISP's
eventually learn to watch the lists themselves, and to act quickly.

There's really no alternative to DNSBL's. Heuristics will necessarily
block correspondence ABOUT UCE, so they're completely unacceptable for
anyone who's concerned about the problem. "Whitelisting", or keeping
your email address secret (which has about the same effect), are
likewise not for me.

Frederick