Hello @JenniSD ,
MP3 and other audio files are not able to be imported into the library, and thus can't be embedded into emails, similar to videos. If you'd like to include a voice-over in your emails, the only way that would really work in the system would be by hosting the file in a cloud drive, and linking to the share URL that drive provides. As far as ling to the voice-over as a video, you can utilize Vimeo or a myriad of other video-hosting sites, if you'd prefer (see our insert video article for instructions).
Keep in mind with either the linking or video block methods, these would not embed the voice file into the email, they'd simply be linked to the host site. For more info on this feature request, as well as voting and voicing use cases, please see this Feedback thread.
See also:
Inserting text links
Inserting image links
Inserting button links
... View more
