If this is the first time e-mailing your Kindle, you need to find or set the Kindle e-mail address (something like yourname@kindle.com) and add your existing support@scribl.com e-mail address to the list of sender e-mail addresses your device will accept.
Amazon provides general instructions here: https://www.amazon.com/gp/sendtokindle/email, or you can follow our summary:
Go to your list of Kindle devices and apps: https://www.amazon.com/myk
To the right of the "Manage Your Content and Devices" heading, select "Preferences".
Scroll down to the heading "Personal Document Settings" (about half way down the page)
NOTE: If you are using a device other than a Kindle, and you don't see your device listed, it is probably not supported. In this case, we recommend using a standard EPUB reader for your device, like the built-in iBooks on iOS devices or Edge browser and ebook reader on any Windows 10 device.
Note the e-mail address associated with the device you want to use. This is the address you must enter on Scribl as your "Kindle e-mail address."
Further down, under "Approved Personal Document E-mail List," click "Add a new approved e-mail address."
Enter support@scribl.com in the popup and click the "Add Address" button. This tells Amazon to accept e-mails from Scribl to your Kindle.
On your Kindle device within a few minutes of e-mailing the file to yourself, you should see it appear in your Kindle library on that device. Read it just like any other book in your Library.