Replying to @gutenberg_org@mastodon.social
@gutenberg_org
No, use USB transfer and a free program like Calibre to make azw3/KF8 from epub2 or epub3! The azw3/KF8 is is closer formatting to epub than kfx.
Only K1, K2, and DX family need use actual mobi files, which Calibre can also make.
Send to Kindle uses the Internet twice, gives Amazon a copy, is limited in file size and poorer quality than Calibre conversions. It's Amazon surveillance.
I've converted Gutenberg files for over a decade with free Calibre. Mac, Windows & Linux.