The birth of the SPBL

Without much fanfare last week a new weapon in the anti-spam arsenal was released and a new industry term was born, the SPBL (Service Provider Block List). The brainchild of Rob McEwen of invaluement the new service enables email server administrators to block spam emanating from the shared IP customers of ESPs (email service providers) .

In its first iteration the SPBL addresses just one ESP spam, that is mail sent from the SendGrid Twilio platform. But Rob has plenty of plans for this new service.

The Problem

Whilst every postmaster dreams of zero spam reaching the mailboxes they manage, it is an incredibly difficult task at times. Huge progress has been made over the past decade and smarter filtering decisions are being made and everyone is experiencing a less crowded inbox as a result. Much of this innovation is based around content filtering decisions as IP based blocklists have become less effective against a certain subset of users.

Some email service providers are just too big to block for many sysadmins. An ESP may have dozens of IP address shared by tens of thousands of clients. Despite what many deliverability bloggers may have told you over the years, dedicated IP’s are not the best solution for the vast majority of email senders.

Spammers are an innovative bunch and will try and find every loophole possible, every backdoor or quick hack to achieve inbox for their unsolicited messages. Recognising the legitimate usage of shared IP ranges, and the ability to manipulate these shared IP reputations to their own advantage.

The Solution

A surgical approach to identifying the sender/account behind a message and being able to block the message at the gateway before having accepted the entire message. This is a massive overhead saving for postmasters, and when managing millions of hundreds of thousands of mailboxes this makes a huge difference in terms of performance and resources.

Atro Tossavainen of Koli-Lõks OÜ explains the value of the service succinctly, saying on Linkedin “invaluement‘s services allow email recipients to go further from the level of who owns the IPs or domains, removing individual customers of senders whose customers can be methodically recognized from the headers with surgical precision.”

Find out more

More details about the service and how you can implement yourself is available here:

At the moment implementation may be a little technical for some, however there is a SpamAssassin plugin in development. as the SPBL and the planned plugin are free donations are being sought to offset the costs of future development.