RBL General Information

Sago Networks operates a custom Real-time Blacklist List of known spammer IPs. The list is generated by extrapolating all IP addresses that send out servers at least 30 spam emails, with no legitimate email. The list is extrapolated from both our corporate and shared mail servers, as well as many of our managed customer mail servers. In this regard, the list is custom tailored to the type of spam that would be seen all across Sago Networks. The list is updated once per hour, per server.

Spamassassin Cluster

Sago Networks has a spam-processing cluster of ten servers, including two hot-failover load balancers. The cluster is segregated into two distinct sub-clusters. Each cluster is comprised of three SpamAssassin 'processors' and one dedicated mySQL server. The SpamAssassin processors are mySQL-based so they share a common database of known spam. Both mySQL databases in each sub-cluster were populated from the same bayesian database at the time the cluster was created. The spam-filtering load is evenly sparsed between both sub-clusters so that each sub-cluster has an equal opportunity to learn from the incoming spam.

It was found in the last six months that it is more efficient to offload the spam processing to a dedicated SpamAssassin cluster, than to have the mail server itself process the spam. This results in reduced resource utilization. For dedicated mail servers, this equates out to more resources for additional concurrent incoming mail connections.

We do offer access to this dedicated SpamAssassin cluster for our customers, as an additional service to your monthly statement. Please contact This e-mail address is being protected from spambots, you need JavaScript enabled to view it for more information. This service is available only upon request, and to active Sago Networks customers. Access is restricted by IP address.

Extrapolation Technique

The extrapolation technique used to come up with the RBL has changed over time. The current method involves an hourly cron script that runs on each mail server. The script examines the maillog and looks for any mails that have passed through the mail server that do not have a database entry. Every email that passes through the mail server will be inserted into the mySQL database, along with the SpamAssassin score, and the original IP address that passed the email on to the mail server. In addition, if the message was flagged as spam, a counter is incremented for the IP address in question. If a total of 30 spam messages are passed through the mail server, with 0 legitimate messages, then the IP address is added to the blacklist.

Removal from the Sago RBL

Sago Networks understands that no spam-filtering method is fool-proof, nor is it 100% accurate. As such, we understand that there is a possibility a legitimate email source may be blocked by our RBL. If you find yourself in this situation, you will need to use the Database Lookup link above to first look up your IP address in the database. From there, you'll be able to submit a request to us to have your IP address removed. If your request is approved, all counters for your IP address will be removed.