Repeat notifications for text and email messages

Under HKCU/ControlPanel/Notifications find the following keys for Email and Text messages:
A877d65Axxxxxxx
A877d65Bxxxxxxx
Also find Key 15F11F90xxxx for reminders.

Copy the Options value from the Reminders key and overwrite the options value in both email and text message keys with this value (1073741853)
Once you do this, go to start - settings - sounds and notifications - notifications.
under events, select new email message OR new text message and you’ll notice that th repeat option that was grayed out is now enabled and can be selected