Here is documentation on how to send emails with your Mendix app.
Download the email with templates module: https://marketplace.mendix.com/link/component/259 and follow the documentation:
This is a good way and after some practice you should be able to implement it within 1 hour.
Also, you may want to try a pre-configured email app service. https://marketplace.mendix.com/link/component/118393
This service takes away the pain of complex setups, it's now available for trial and subscription.