If you’ve ever tried to upload an ebook in .MOBI or .EPUB format with the WordPress Media Uploader, you will have noticed an error message appear. Something along the lines of “Sorry, this file type is not permitted for security reasons”.
The only way then appears to be to ZIP the file and share it. That’s not a great experience for mobile users, who would simply like to click on a file and open it in an application such as iBooks or Kindle.
The solution to this puzzle lies in adding the required mime types to WordPress, so that these file types are allowed.
Let me show you how to do it in this article.