This will be a bit tricky!
You can still subscribe a calibration management plan however you will not be able to receive automated 6 monthly reminders.
The whole idea of how easy the management plan is has to do with email, and we have to use the email method to confirm the your shipping address each time.
Unfortunately, we don't have a solution for customers without an email yet. However if you'd like to use this method and would like to discuss potential alternative solutions, you can contact us by clicking on "New Support Ticket" above.