When you purchase an e-book from the Amazon.com bookstore using your Kindle, the file is provided in a proprietary format that supports author licensing options and digital rights management (DRM) protection. The Kindle can also accept e-books in other formats, including files in the Mobi Reader's MOBI format. Transferring your collection of MOBI e-books to the Kindle is accomplished by e-mailing the files as attachments or uploading them via a USB cable.
Press the "Menu" button on your Kindle's keyboard and open the "Settings" page using the five-way controller.
Write down the Kindle's unique e-mail address displayed on the "Settings" page.
Attach the MOBI e-book file to an e-mail and send it to your Kindle's e-mail address. It's not necessary to specify a subject or add any text to the body of the email. Upon receipt of the email, the MOBI e-book will be added to your Kindle and will automatically appear in its library.
Connect the Kindle to your computer using the USB cable supplied with the device. Your computer will automatically detect the Kindle and assign it a drive letter.
Open the Kindle's drive on your computer. Inside you will find three folders -- "audible," "music" and "documents."
Copy the MOBI e-book into the "documents" folder by dragging and dropping it or using the "copy" and "paste" commands in the folder's "Edit" menu. Once the file has been copied, you can disconnect the Kindle. The MOBI e-book that you just uploaded will be instantly available in the Kindle's library.
You can transfer or e-mail multiple MOBI e-books at once. In addition, e-books can be combined into a compressed ZIP file before e-mailing them to the Kindle. The device will extract the compressed e-books automatically upon arrival.