When you receive an email notification about a new voicemail, an attachment is included. This attachment is not a valid file that can be opened. The audio has been removed, but due to some limitations in the code our system still sends an attachment with nothing in it.

Email was designed as a text-only protocol in the 80s and handles audio and video very poorly or not at all. For example, one voicemail can take up as much space as 60 emails, and one 30 second video on a modern iPhone is around 600MB which is 30x the email attachment size limit. Our email servers are limited in capacity and when mailboxes get too large, our Vault system moves items to alternative storage to keep mailboxes small which helps preserve Outlook fast. Slow Outlook is a common complaint, so we do our best to keep mailboxes low by blocking audio and video via email.