I just finished a writeup which covers anti-spam methods using:
- route filters
Ack! You put 'datablast.net' in their Marty! 
Seriously, we are working on the Datablast problem. Datablast
has basically been victimized by the spammers. While not directly
a part of TIAC, we do support Datablasts servers et. al.
In any event, before blocking Datablast.NET, please give us some
time to correct the problem. For the record, TIAC does NOT
support spamming. Nor does Datablast.NET
Regarding the SpamDomains file: It is based on our experience here
with problem domains and is made with careful consideration. I'm
not particularly motivated to remove anyone from it until the Net as
a whole indicates a domain has cleaned up its act. As an example file,
you should customize it to suit your own local needs; our file is
presented as a courtesy to the community.
But please, don't send me "please remove X cause they're really decent".
Corporate reputations are built on a foundation of cooperation and trust;
when an ISP tolerates bad behavior despite constant complaints from the
community, they quickly lose that trust.
Since NANOG is for technical issues, this is the only "position" mail I'll
post concerning the "who is on the list" issue. Please send me private
mail if you'd like to discuss it further.
Can i deduce from this that you have blocked PSI as well as that datablast
domain? If you use sheer volume of spam-relaying as your measure, PSI's
act is far more unclean. But we block datablast and allow PSI to crap
all over the place because it's expedient to do that. Where does a 500
pound gorilla take a dump?
By the way -- PSI is operating several mail machines that are running
wide-open for anyone who wants to use them for spamming or bombing. The
MTA they are using is not adding the IPs of the originating host to the
header. I have complained to them for two weeks now, but they have done
nothing, poopsie, squat, diddley, nadda, zilch.
Bill
No, you just refuse to cancel an account that you know is being used by
the owner to hack nasa.gov machines, and only give in when your customers
start complaining because they can't irc. (so the circle is round now)
Operational issues? With Linux boxen popping up everywhere there's bound
to be some old installations with broken versions of imapd, sendmail, yada
yada; everybody's network feels ping floods from DS3-connected sites - and
we've all seen "smurf.c".
  Niels
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PIH XXTP SE ICTL, BTIHTKY. <niels@churchofbofh.org>
Note: I do not speak for my employer - they have net.access too.