After years of what they might have to do, Amazon’s modern lineup of Kindles will finally support the ePub file format for books. According to the change you observed Good e-readerAmazon has updated its “Send to Kindle” documentation, saying it will add support for ePub files later this year. At the same time, though, Amazon is also disabling support for the MOBI file format, as it won’t support the latest Kindle features the company wants to integrate.
At the moment, it’s not clear exactly how ePub files will work on Kindle. Will independent sellers and publishers be able to submit their ePubs for distribution? If so, will they need to use Amazon’s own encryption? From the Send to Kindle documentation, the ePub files transferred to Kindle will be prompted not to contain any DRM or else they will not work.
This is a huge boon for the Kindle ecosystem, as ePub files are the most widely used e-book format. Kindle owners had to convert their own files using a tool like Caliber so they could read their books on their devices.
As for the loss of the MOBI file format, it was a bit surprising, even though it’s a really old file format. Amazon acquired Mobipocket, the inventors of the MOBI file format, in 2005. Amazon then renamed MOBI to AZW, and that was usable on devices. If you own e-books in the AZW/MOBI file format, they will still be safely stored and readable on your Kindle – you won’t be able to copy any new books in this format in the future.
source: Good e-reader