I got this email just now sending a mobi to my device.
Dear Kindle Customer,
Thank you for using the Send to Kindle service to send personal documents to your Kindle library. We noticed that the following document(s), sent by you at 01:49 AM on Sunday, June 26, 2022 GMT are in MOBI (.mobi, .azw) formats:
* OldMagic2.mobi
We wanted to let you know that starting August 2022, you’ll no longer be able to send MOBI (.mobi, .azw) files to your Kindle library. Any MOBI files 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 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 format.
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.
If you have any questions, please visit our help page or contact our Customer Service team.
Regards,
Amazon Kindle Support
Kindle Previewer, which they recommended for creating mobi's after removing the option from the submission process doesn't create an epub.
I've never head of a Send to Kindle desktop app. I'll have to try and find it.
But 2 questions are not answered in that email.
How do you create an epub to be able to send to your device?
And what other formats does the Send to Device feature support?
The whole object of sending to the device as a mobi was to see the book on your device as it would actually look.
As far as I can see, the left foot is driving what the right hand isn't doing.
Since they discontinued the Mobi format, nothing among their many facilities is using the same thing. Including the download off the submission page, which is supposed to be an html version but doesn't even have an html file in it.