Much like the singer from the early 2000s, MOBY, Amazon's MOBI file format is gone. The official word from Amazon:
...starting August 2022, you’ll no longer be able to send MOBI (.mobi, .azw) files to your library. Any MOBI files already in your Kindle 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 existing MOBI files you want to read with our most up-to-date features for documents will need to be re-sent in a compatible file format.
Also, compatible formats now include EPUB (.epub), which you can send to your library using your Send to Kindle email address. We’ll also be adding EPUB support to the free Kindle app for iOS and Android devices and the Send to Kindle desktop app for PC and Mac.
You'll notice you can no longer boot a formatted MOBI file from your Amazon dashboard. Instead, you need to download KINDLE PREVIEWER and open your book there (assuming you have your doc as a WORD, PDF, MOBI, ePUB, etc) and then you can export it in Amazon's native KPF format if you're looking to share it with a Kindle Reader.
I've arranged it so MOBI is no longer available as an upload option on AuthorsXP (for the Read and Review program) but you can upload KPF now!
