Joseph Brennan asked:

When we reject a message because it contains a URI that is in SURBL, should our 550 message refer the sender to www.surbl.org? The surbl

Joseph:

I can't speak officially for SURBL, but I'd suggest stating something like the following in the SMTP return text:

"blocked by XXX due to containing a URI listed at www.surbl.org"

where "XXX" = your organization or your spam filter.

The idea is that we WANT legit senders to give SURBL immediate feedback if/when SURBL makes a mistake (which is very rare).

However, SURBL never blocks any mail and we don't want to give users the mistaken impression that SURBL blocked their message. Instead, it is the spam filter provider or mail hosting provider's decision to use SURBL and SURBL's lists comes without warranty or any type of guarantees (even those most deem SURBL to be very accurate and to have extremely few FPs).

BTW - just a side suggestion... I find that the best spam filters employ a variety of spam-catching techniques and strive to NOT score any one particular tactic high enough to single-handedly block a message. Of course, we strive to make SURBL so reliable that most would consider it safe to block a message soley based on SURBL "hit"... but, if applied correctly, following this suggestion will provide the best case scenario in BOTH reducing FPs and boosting spam filtering percentages.

Rob McEwen PowerView Systems rob@PowerViewSystems.com