It came to may attention when I sent my books into Kindle that Amazon is preparing to end support for .mobi and .awz formats. It is a good news so finally you will be able to use the widely used format .ePub with your Kindle.
We are writing to let you know that Send to Kindle will soon remove the ability to send MOBI (.mobi, .azw) documents to your Kindle library. Any MOBI documents already in your library will not be affected by this change. MOBI is an older file format and won’t support the newest Kindle features for documents. Any MOBI documents already in your library that you want to read with our most up-to-date features for documents will need to be re-sent in a compatible format, such as EPUB (.epub). You can send EPUB documents using Send to Kindle for Web, the Kindle app for iOS and Android devices, the Send to Kindle desktop app for PC and Mac or your Send to Kindle email address.