Configure Calibre to use Gmail's servers to send the email to Amazon.
In your Gmail account, turn on 2-Step Verification and then generate an App Password for use with Calibre. Here's Google's Help on how to do that:
https://support.google.com/accounts/answer/185833
In the Calibre email setup screen, the "Send email from" should be the Gmail username that's whitelisted in your Amazon account, Hostname is smtp.gmail.com, Port is 587, username is the Gmail username again, Password is the app password you generated specifically for Calibre, and TLS is selected.
If you use "ginnybo" for both your Gmail username and your Kindle address, then Amazon will send you a verification email for each book before it will deliver it to your Kindle. If you want to avoid that, change the Kindle address to some more random string of letters and numbers.