Ishmail is a program for people who get a lot of electronic mail.

Written by Jonathan Helfman and Charles Isbell for AT&T Labs-Research, Ishmail has been used continuously by several dozen people for several years. Ishmail was patented on May 28, 2002 as US Patent 6,396,513, “Electronic message sorting and notification system.” Ishmail was implemented in Emacs Lisp (Elisp) as an extension to the Emacs Rmail package.

There is also a Java implementation of Ishmail, thanks to Gavin Bell.

Do you really want to be informed that “you have mail” every time you get a message? Sometimes you do, if it's from someone important. But many messages are easily identified as being unimportant. For example, you might only want to be informed when you have more than ten unread messages from some senders (like mailing lists) or when the oldest unread message containing the string “viagra” is more than thirty days old. Ishmail sorts messages into mailboxes according to customizable rules and orders mailboxes by alarm status and user-specified priorities. Ishmail supports independent alarms on each mailbox with customizable alarm thresholds.