This module supports links from any kind of Unix mailbox (mbox). To use this module, make sure that planner-unix-mail.el is in your load path and add this to your .emacs (or _emacs):
(require 'planner-unix-mail)
Unix mail URLs are of the form:
;; mail://PATH/TO/INBOX/message-id
Annotations will be of the form:
[[mail://PATH/TO/INBOX/E1AyTpt-0000JR-LU%40sacha.ateneo.edu][E-mail from Sacha Chua]]
planner-unix-mail.el does not define any interactive functions or create any new keybindings.