K4 MailPush - how to email books to Kindle in 2024?

[Darthagnon]

I recently discovered MailPush (Chinese Github, my English fork), which seems to offer a more decentralised way for me to email myself docs, my Mum devotional lessons, etc. without logging in to Amazon or depending on them to convert my docs to Amazon formats. I use KOReader, so would rather keep them as docx.

Though it sounds amazing, I have had absolutely no luck getting it to work. All menu options give me "/tmp/klauncher_background-803463509291224482.sh: line 2: mailpush.sh: not found", as tested on 2 different Kindles, my own K4 and a friend's Kindle Basic 3 I was setting up.

Can anyone advise on how to get this tool working? Any help would be greatly appreciated. Most of the other tools by Guo Yong Zhi work perfectly as far as I can tell; his Filebrowser for Kindle is amazing, and the menu entries seem to be fairly standard...