It happened to others on this forum, now it happens to me: the printing company (which I have not chosen) sent me the following message:
The interior file cannot be manufactured due to unlicensed/unembedded fonts. Please make the following adjustments to your file and upload it again.
The following fonts should be replaced with another font or fully embedded in the file. Alternatively, characters can be converted to outline, which will make it a vector that will remain as submitted.
followed by a list of 29 (!) fonts that cover 99.99% of the text of my document (grosso modo, only Computer Modern fonts, seldom used, have escaped this witch-hunt).
As already mentioned in posts in the forum, the last line of page 40 of the dvipdfmx manual explicitly says that "dvipdfmx does not support full embedding. Only subset embedding is supported".
This seems like a Kobayashi Maru situation: the printer wants fully embedded fonts and dvipdfmx refuses to do so (not by technical impossibility but by choice).
Let me add that it has nothing to do with licensing: in the list of "forbidden" fonts there is also FreeSerif (which is free, by definition) and even an ad hoc font called Unnamed-Medium I created myself. And also ZapfDingbats and Symbol fonts, which should be part of the glorious 35 standard fonts.
What would you advise me to do?
I used XeLaTeX to create the PDF files.