The SpamDigester is a server based system that takes messages marked as Spam by the SpamAssassin email filtering system, and drops then into a central quarantine instead of forwarding them to the user for further header based filtering.
The messages are then condensed into a Digest E-mail which contains the sender, the Spam score, the Subject and the first line or two of the message. The Digest is an HTML formatted email (with a corresponding page for email clients that won't submit a form from within a message) that you can submit from your Email client, and any messages that were mistakenly tagged as Spam will be forwarded to you immediately.
There are several benefits to using a central quarantine for Junk email: Message aging (i.e. if the message has been in quearantine for more than a set amount of time, delete it), and minimal user comtact with junk mail (which translates into more productive time). In addition, if your users don't often clean out their Junk email folder, your server may be holding several Gigabytes of junk mail that is slowing things down and hogging disk space!