[To breakdown] Api: Send mail

[ElSalvo96]

We need to send some emails to our client, like:
First login --> Thanks! / Talk with us / our socials
After one month, you are no longer logged --> Send a reminder.
When a user buys a premium, --> Thanks and bla bla bla...

We need a text for all of this action.
We need to understand how to send mail.
We need to setup a cron job for checking and sending mail when needed.