This is updated version of the ThunderLink extension that has been modified to work with PostBox.

The main changes are:

• It actually can be loaded into PostBox :)
• The links use the protocol x-postbox-message which is inherently supported by PostBox
• The menu items are on the menubar under Tools rather than on the message. This is so I can assign keyboard shortcuts in OSX and also because message menus overlays don't seem to work in PostBox (I suspect because they gave it a different XUL id).
• You have two choices of what to copy to the clipboard
  • Plain text with the message subject followed by its link
  • A rich/HTML link with the message's subject as its text