Thu Apr 8 18:30:59 PDT 2004 — Updated Email Filtering. We have employed a multi layered system to fight spam for quite some time. While SpamAssassin and Virus filtering have gotten all of the recent attention, we have also used the MAPS RBLs, or real-time blacklists, to reject mail sent from known spam sources.
In response to the ever increasing volume of spam that has been reaching our customers inboxes we enabled use of two additional blacklists earlier today. The SBL and XBL from spamhaus.org have reduced the total volume of email we accept for customers by nearly 50%.
We have also been hard at work improving our own local blacklists to target many Cable and DSL provider’s dynamic clients – the biggest source of spam today. There was a brief error with this list earlier today where a number of large blocks were incorrectly added resulting in the bouncing of some legitimate senders.
In addition to these steps, we’ve also launched a new member tool which users can use to choose additional RBLs to be used to filter their email or opt entirely out of our MTA level filtering. Please use caution with this tool, some of the RBLs provided are very aggressive and will block legitimate Email. Unless you are familiar with the RBL’s listing policy and understand the ramifications it’s best to leave the settings at default. The tool is available at sonic.sonic.net/membertools/spamlist.pl
Please see news://news.sonic.net/sonic.antispam for a complete discussion of the new filters and tool. -Sonic Operations