Blocking Spam with SBL/XBL

As part of our efforts to reduce the amount of spam that impacts our users we have adopted the use of SBL/XBL to eliminate mail coming from problematic mail sources. Mail coming from servers listed in SBL/XBL is rejected outright at connection time.

Use of SBL/XBL in combination with our implementation of Spamassassin spam scoring should help our users save time and mailbox space.

The Spamhaus Block List (SBL) and Exploits Block List (XBL) are realtime databases of known spam sources provided by the Spamhaus Project. The SBL contains systems that are known to be spammers, and the XBL contains systems that have been exploited for purposes of sending security exploits and forwarding spam. These lists allow email providers to identify messages coming from problematic systems. If you'd like to learn more about SBL/XBL please see Spamhaus.org

When a message is rejected for being on the SBL/XBL the sender will receive notification stating that the mail has been rejected. This message will contain a link to information about the Spamhaus system. The intended recipient will receive nothing. This arrangment prevents the recipient from being inconvenienced while alerting the sender so that in the extremely rare case of legitimate mail being blocked, the sender may seek an alternate means of communication with the intended recipient.