Package: greylistd (0.8.6) [universe]

Greylisting daemon for use with Exim 4

This daemon provides a simple greylisting implementation for use with the Exim Mail Transport Agent (MTA), version 4.

Greylisting is a simple but highly effective means to weed out messages that are being delivered via spamware/ratware tools. The idea is to establish whether a prior relationship exists between the sender and the receiver of a message. Most of the time it does, and the delivery proceeds normally.

On the other hand, if no prior relationship exists, the delivery is temporarily rejected. Legitimate MTAs will treat this response accordingly, and retry the delivery in a while. In contrast, ratware will usually fail to retry the delivery in a normal fashion. As a result, greylisting is currently more than 90% effective in blocking incoming junk mail, while nearly all legitimate mail goes through. For more information, see Evan Harris' whitepaper at:

  http://projects.puremagic.com/greylisting/

This daemon listens for sender and recipient data on a UNIX domain socket. Your MTA would query the daemon during the incoming SMTP transaction, and accept or defer the incoming message depending on its response.

This package contains a script to configure support for greylisting in Exim 4. It may be possible to use greylistd with other MTAs as well, though some work will probably be involved. Postfix users may want to check out the "postgrey" package instead of this one.