Set up a Test SMTP Provider
Auth0 recommends you setup a fake SMTP server while in development or testing that you can use to check delivery and view how emails will appear without the risk of spamming your users.
You can either setup your own SMTP server, or use a services like mailtrap.io that are designed for this purpose.
Fake SMTP Services
Frameworks & other tools
Auth0 has only tested mailtrap.io in this scenario.