MailPriority is a plug-in for Mail.app on Mac OS X providing a simple interface to
* set Priorities for outgoing messages by setting the X-Priority header
* organize your mails by color-coding messages
* request Receipts by setting the Disposition-Notification-To header
* permanently show th 'Reply-to' and 'Bcc' fields when composing a new message
(10.2 only).
Features:
* Once started, the 'Edit' menu in Mail.app has a new item 'Priority' allowing to set a Priority between none and 1 to 5.
* In the Compose and Reply window, you can add toolbar items (by customizing the toolbar) to set the Priority (off/level 1..5) and to request a receipt.
* In all other windows, you can add a toolbar item (by customizing the toolbar) to show the Priority of a selected message.
* MailPriority also adds a new Preferences panel which lets you choose a default Priority for new messages and a color scheme for highlighting incoming message priorities.
* Cntrl-Click on the message list shows a new contextual menu item 'Colorize' which allows to assign colors to messages.