James Eagan, the creator of the Missing Attachments plugin, has written a tutorial on how to make a Mail.app plugin.

He writes:

In the course of writing my email un-attachment plugin for Mail.app, I found that Apple has a capable, but entirely undocumented, plugin API. I’m providing this tutorial in the hopes that it may be useful to anyone else considering implementing a plugin for Apple Mail.

Personally, I can’t understand a word of it, but many Hawk Wings readers with Python skills will no doubt find it excellent.

A poster on the macOSXHints forums has already used the tutorial to create a plugin that does something with signatures in Mail.app (adds a random signature to each email from the UNIX program Fortune?).plugins, tutorial, howto, signatures, python, mail.app, apple mail, fortune

One of the “Mac heads” at Skype has produced a tutorial on how to insert a Skype graphic into an HTML signature for Apple Mail.

This walk-through is more detailed than the tip posted on macOSXHints and is useful even if you want to insert a different graphic into your signature.

UPDATE: You now need a Skype account to view this tip on the Skype site. And one with more privileges than I have.skype, signatures, email, graphic, walk-through, tutorial, howto, mail.app, apple mail, tips, HTML