Over the past several months we’ve watched a marked increase in the spam making its way through our filtering. And we’re not alone. Spam volume has increased over 6 times since October 2013 globally and many spammers have become increasingly sophisticated in thwarting filters, explicitly testing and tuning delivery through common systems to ensure their spam reaches their targets. In response, we’ve completed several upgrades that have had a big impact reducing spam in our inboxes.
We finished a migration to our next generation MX servers last week. The new MX servers feature a completely rewritten custom policy enforcement engine. Like most MX filters, it makes heavy use of a collection of reputation services in conjunction with policies like rate limits and checks for basic compliance. There’s one important difference with the new system: it only allows customers to opt-out of the filtering where our old MX filters allowed for some per user customization. When a customer opts out, we’ll make our “best effort” at excluding a customer’s inbox from any filtering.
We’ve also made a couple of important changes to our SpamAssassin installation including the integration of a commercial plugin. This, along with a redoubled effort to maintain our own set of custom rules, has significantly increased its accuracy. We hope these changes have made as big an impact on your inbox as they have on ours.
Customers may opt-out of the new MX filters and adjust their SpamAssassin preferences using the Spam Configuration membertool. Please join us in the forums if you have any questions.