Backspin Feedback for "SBC makes DSL, er, exciting" (3/21/05)

Regarding the Backspin Column "SBC makes DSL, er, exciting" we received the following from a "robwfutura" (no name supplied so e-mail address less domain used) on Friday, March 25, 2005 2:35 PM:

This guy really needs a clue. He has absolutely no idea how the spam organizations are working. He needs to pull his head out of the clouds and do a little research. What he'll find is that "this ridiculous and ineffective program" combined with other ISP's doing the EXACT same thing, has pushed a decrease in spam that is somewhere between 15%-25% depending on who's figures you believe. I will definitely start ignoring anything quoting this source.

Mark Gibbs's response:

Wow. That's a remarkable amount of hostility over a subject that you wouldn't think could get someone so riled up. From the research I've done I have yet to find a definitive answer as to the effect that port 25 blocking is having on spam reduction. In fact I have found no evidence yet for any drop in the overall spam percentage and if you believe the MessageLabs statistics (click on the "spam" tab) the overall level is still trending (albeit slowly) upwards! If robwfutura would care to reply with where he found his figures of 15 to 25 percent spam reduction I'd be very interested.
I suspect that Port 25 blocking seemed to make sense as a way of blocking zombies (see MessageLabs commentary) but the contribution of zombies to spam appears to be dropping for reasons unrelated to port 25 blocking.

Even the zombies are getting around port 25 blocking! Again according the MessageLabs: "In recent months, spammers have been changing tactics in order to side-step anti-spam counter-measures being introduced by ISPs, such as SMTP (TCP port 25) traffic blocking. For example, Send-Safe is now able to route spam email by redirecting the email traffic from the spam trojans via each compromised PC