Got the first version working
It creates a reminder in 📥 Indbakke (change to your preferred folder) with the name of the sender and the subject of the mail. In the body of the reminder it pastes a link to the e-mail.
From what I can find on Google, it is not possible to insert the link in the URL of the reminder...
tell application "Mail"
set _msg to item 1 of (get selection)
set _messageURL to "message://%3c" & _msg's message id & "%3e"
set _msgSubject to subject of _msg
set _from to sender of _msg
set _name to extract name from _from
set theInfo to (_name & " - " & _msgSubject)
set theLink to _messageURL
tell application "Reminders"
set mylist to list "📥 Indbakke"
tell mylist
make new reminder at end with properties {name:theInfo, body:theLink}
end tell
end tell
end tell