Thank you Mark.
I browsed the Django Admin web interface (https://[list server]/admin) (which is actually partly in Danish for some reason) and found that in "Accounts" > "E-mail address" it is possible to uncheck "Verified", but it doesn't seem to do anything. When that user logs in again, the "Verified" check box is re-checked, but no confirmation request mail was sent to the user.
Also in the Django Admin web interface under Authorization -> Users it is possible to add "account | email confirmation | Can change email confirmation" to the user's rights, but I am not sure what those do. I suppose it is to add the right to do the above mentioned.
If removing the "Verified" does not make the user reconfirm, what is it for then (just trying to understand)?