Excessive Hyphenation added by Amazon

[Olders]

I am hoping somebody may be able to give me some tips or advice on overcoming this issue:

On some books (but by no means all) when I email the epub file to my kindle (or open it in Kindle Previewer) the conversion process adds a huge amount of hyphens, which makes it very difficult to read.

I have had an extensive play with re-formatting the 'problem' epubs using calibre to add/remove soft hyphens etc and they look perfect in the calibre reader. None of these changes seem to have much effect though as once converted by Amazon, they always end up with masses of hyphens. Sometimes most lines end up in a hyphen!

The books use 'enhanced typsetting' are viewed at size 4 in the Bookerly font and are left justified.

I suspect I am beholden to Amazon's 'hyphenation algo' in the main but I just find it strange that some books convert with almost no hyphenation (and still look perfect), whilst others are a total mess!

Is there anything I can do by editing CSS etc in Calibre to try and minimise or improve/lessen the amount of hyphenation amazon implies during conversion?

Any help or suggestions much appreciated!

I have also posted this same question on the Calibre forum, so apologies for any duplication!

[issybird]

Don't crosspost.