Mail.app: Get URL for selected message with AppleScript and TextExpander

I often use message://<message-id@example.com> URLs to reference a specific email in OmniFocus or Evernote: clicking one of these URLs will automatically open up the source message in Mail.app.

There's not a great way to get these very handy message URLs without AppleScript, so based on this SuperUser answer, I created a TextExpander snippet.

Now, when I type xmsg, TextExpander will insert the message URL for the selected message in Mail.app into whatever application I'm working in.

Here's the TextExpander snippet, and here's the AppleScript:

tell application "Mail"
	set selectedMessages to selection
	set theMessage to item 1 of selectedMessages
	set messageid to message id of theMessage
	-- Make URL (must use URL-encoded values for "<" and ">")
	set urlText to "message://" & "%3c" & messageid & "%3e"
	return urlText
end tell