Originally Posted by Adam B.

Thanks for pointing me in the right direction. But following your instructions didn't work. (MMS were not delivered to my phone)

I did get it working with the following though:

Changes

1. You will need to Delete PC10 in the
   HKEY_LOCAL_MACHINE\Security\PushRouter\Registrations\ByGenericId registry key
2. Instead of using the 80409F46E414C801 ID, you will need to copy/paste the ID from the ByGenericId section relating to MMS.

I received an MMS message without a problem that way. And, I only got one notification.