First go to the My Settings page and scroll to the “Mobile Uploads” section at the bottom of the page. Click “Refresh” next to the Add By Phone email address and send your next video with the new email address.
If this does not work, try resending the video from your computer’s email client. Bear in mind that if you are trying to upload content by phone on a network with a custom URL, the network will need an MX record to work properly. If you need additional help, let us know from the Support link on your dashboard, and we’ll get to the bottom of it!