Android - How can I read epub or mobi files with Kindle?

I will answer my own question in the hope in helps others: I just had to reboot my device, and now when I start Kindle the MOBI files which I had copied to the Kindle folder are present in the main screen.

So obviously the Kindle application must be restarted when you add ebooks to its folder (without downloading them via the Kindle store).

UPDATE

Added the Kindle folder:

/sdcard/kindle

Force closing and/or clearing the data, does not bring up an EPUB file I just copied to the folder. Will let you know after some more testing.

UPDATE 2

For those interested: the Calibre software, can convert any e-book between numerous formats (including EPB and MOBI). So, if the EPUB format is not recognized, just convert it to MOBI and use the converted file.

For my Nexus 5x which doesn't have an SD card, I needed to create the folder /storage/emulated/0/kindle and place my .mobi files there. Opened up Kindle app, and they are there!

If you are wondering where to put those .mobi files (or perhaps any other files that your android kindle app can read) if your Kindle app is located in the external storage (external sd - card), just put them at:

Android/data/com.amazon.kindle/files/amzn1.account.x

x: is a 28 characters long string that will be different for each user