@everlastingrocks and it's not just for "did you get that memo" -- I like to copy URIs of things into my diary in Zim Desktop Wiki. Lotus Notes' desktop client had message URIs, and it would respond to a "notes:" URI executed on the desktop. You had to twiddle it to get the URIs out of it, but they were there. And they were stable and it doesn't matter what folder the message is stored in.
But, it wasn't the "Message-Id". I don't think they were stable across different users' databases.
@progo
And someone has already thought of this:
http://messageidfinder.mozdev.org/
@everlastingrocks Cool. Just needs functions to get URIs out of message view forms in Thunderbird and respond to URIs from the shell command line parameters.
@everlastingrocks Yes. IIRC Message-Id is created before the message is ever first sent. Everyone who has a copy has that same message ID. Any client could index that value and be setup to handle my suggested "email:" URI scheme.