Originally Posted by pdurrant
Presumably you need the mobi for upload to Amazon. In which case, you'll need to use Kindlegen. And it is possible to make an ePub that works well with Kindlegen to generate a Kindle/Mobipocket file.
You should certainly read the Amazon Kindle Publishing Guidelines
which is the main documentation for kindlegen.
This will describe how to format the XHTML/CSS2 in the ePub for best results with KindleGen.
Thank you pdurrant for the link to the .pdf! That's a read I was looking for, it'll help me to build proper EPUB files.
What triggered my initial question were repeated failed attempts to produce functioning MOBI files, but I think I'm now getting to the point to restrain the EPUB sufficiently.