A site I built that allows participants to email content regularly generates error messages on attached mp3 files, e,g,
Some attachments were rejected from the following WordPress.com Post by Email: - Nimis Kahpimotate Presentation part 2.mp3 - Invalid file type
Although .mp3 is supposed to be a valid upload type (I can upload mp3 via Media Library). It is no a file size issue, we have max uploads set to 100Mb and these are less than 20.
Also, the error message does not help much because it does not give a link to the post so I can fix it.