A MOBI file is an e-book format devised and popularised by Mobipocket Reader, which was subsequently bought by Amazon.com. The MOBI file format is the basis for both Palm's PRC document files and Amazon.com's AWZ e-book files, making it fully compatible with the Kindle e-book reader and Kindle software applications. You can transfer MOBI e-books to the Kindle from a computer via e-mail or by using the Kindle's USB cable.
Connect the Kindle to your computer using the Kindle's USB cable. The computer will recognise the Kindle as a mass storage device and automatically assign it a drive letter.
Open the Kindle's drive on the computer. Three folders will be present in the Kindle: Audible, Music and Documents.
Drag and drop the MOBI file into the Kindle's Documents folder to load it onto the device. You can disconnect the Kindle when the file transfer is complete, and the MOBI file will be immediately accessible in the Kindle's library.
Press the "Menu" button on the Kindle's keyboard. Select "Settings" using the five-way controller and take note of the "@kindle.com" e-mail address displayed on the "Settings" page.
Create a new e-mail message on your computer and add the MOBI file to it as an attachment. Address the message to the device's "@kindle.com" e-mail address and send it.
Press the home button on the Kindle and wait for the MOBI file to arrive. It will be forwarded to the Kindle when the email is received, and the file will be automatically added to the device's library. Delivery of e-books via e-mail typically takes no more than a few minutes.
You don't need to add a subject line or text to the email when sending a MOBI file as an attachment. You can send multiple MOBI files to the Kindle at once, either via USB or as e-mail attachments.
The Kindle cannot read copyright-protected MOBI files. If you're transferring MOBI files to the Kindle as a compressed ZIP file, the ZIP file must be unprotected.