[Mimedefang] [OT] SBL

[Josh Kelley]

I realize this is a bit OT, but I've seen SBL recommended here before, 
and I'm not sure where else to ask...

I'm trying to reconfigure our mail server to start blocking spam instead 
of tagging it with SpamAssassin and trusting our users to set up their 
own filters based on SpamAssassin.  Blocking messages based on the SBL 
seemed like a good first step.  In the week or so since I've started 
using the SBL, it's caught about half of the incoming mail to our 
campus, but it's also caused 4-5 false positives (a spammer's company 
that happens to put out a good newsletter, legitimate mailing lists 
hosted by spammers, a legitimate company that uses a spam-friendly ISP 
as their hosting provider).  This surprised me, since I was under the 
impression that the SBL was probably the most trusted and most 
conservative of the blacklists.

Should I give up on blocking via the SBL?  Or should I just accept that 
if I'm going to block mail, I'm going to block a few legitimate ones by 
mistake?  I know that others on this list use the SBL - have you had any 
similar problems?

Thanks.

Josh Kelley