macOS Embed and Find Arbitrary Tag in email using mailto: link?

[ArtOfWarfare]

I have a button in my app which opens a link which is a mailto (so it launches Mail with a subject and address already filled out.)

I was curious if there was a way I could include other hidden tags in the mailto so I could collect other information from emails sent using the link, IE, which version of my app they're running. If I simply had that kind of thing in the subject or body, the user could easily/accidentally just erase it.

Beyond just including that in their email, how could I then read it when I receive the email?

 

[chown33]

Define a different mailto address for each version of your program. E.g. <feedback101@example.com> <feedback103@example.com>.

This assumes you have control over your recipient email addresses.

If that's too difficult, use an HTTP url with a query-string containing version-number. E.g. http://example.com/yourapp/feedback/?vers=103