Send to Kindle Service dropping mobi format support

Amazon has advised that its Send to Kindle server will no longer process mobi and azw files effective August 2022. I use this service to send news downloads to native Kindle wireless devices. The native Kindle OS has a special Periodical toolbar and heirarchical TOC view of the articles in a mobi news downoad which is very useful - but not available on a Kindle for epub format nor on any Kindle tablet versions for any file format. The Periodical Toolbar is attached for reference.

Is there an alternate to the Send To Kindle via Calibre 'sharing books by email' that would transmit mobi to a wireless Kindle device? Thanks.

Attached Thumbnails