Semi-related: I wrote a fb messenger bot [1] which can send any ebooks (including epub) to your kindle. It's handy if you've only got access to an epub, and a bit less clunky than sending via email. [1] https://m.me/kindleebooksender
Just so you're aware, I added it and Messenger automatically sent the "Get Started" text, and the typing animation ran for about 30 seconds until it stopped with nothing happening.
Hi there! Send me your ebooks and I'll send them to your Kindle.
To get started, I'll need you to first tell me your Kindle's email address.
This can be found on your Kindle management page: https://www.amazon.com/gp/digital/fiona/manage?ie=UTF8#pdocSettings
(ending with @kindle.com)
Will look into this, thanks!