To go along with my [Create Calendar Event from Email on Mac w/ Notes and URL) post the other day here is an AppleScript routine that will create a Reminder from a highlighted email message.
It is based on the great code by Michael Kummer with some tweaks. The main change is to remove the default search for an existing Reminder as this was slowing down the creation as the search can take from about 5-30 seconds. Now if the email is not already been flagged it will go straight to the creation step.
Hope this is of value. I use it in Keyboard Maestro in conjunction with other Mail scripts as per David’s “working contexts” concept, makes for a great email workflow.
Latest version can always be found on Github.