Supabase is a popular service that allows to easily implement authentication.
Remember to switch to the branch supabase in the Shipped repository to leverage the Supabase code.
Sending emails for Supabase Authentication
Supabase has recently changed their policies in terms of email sending, and in order to provent spam, they allow to send emails only to the member of the Supabase Organization Team (check yours here) and it is intended to be used for testing purposes only.
For production use, it requires you to configure a custom SMTP.
There are several services you can use to send emails.
A non-exhaustive list of services that work with Supabase Auth is: