Originally Posted by HarryT
It's not a Mobi file; it's a KF8 file.
Actually, it's both.
I used KindleGen 2.8, which creates a master .mobi file that contains both a regular .mobi file and an .azw3 file. (KindleGen also attaches the source files, which can be extracted with 7Zip
But you are of course right. The OP needs to convert to AZW3 not MOBI.
I did some experiments and found out that eInk Kindles actually support Arabic vowel signs, if you keep the styles simple.
(Unfortunately, you cannot embed Arabic fonts.)
To automatically generate a master .mobi file, download Kindle Previewer
and open your .epub or .html files with it. Kindle Previewer will automatically generate a .mobi file.