Please what should I install to send e-mail?

Hallo,

I have configured the Cloud in the following way:

Step 1 - I installed Linux, nginx, MySQL, PHP (LEMP) as shown in this guide:

https://www.digitalocean.com/community/tutorials/how-to-install-linux-nginx-mysql-php-lemp-stack-on-ubuntu-14-04

Steep 2 - I installed Phpmyadmin as shown in this guide:

https://www.digitalocean.com/community/tutorials/how-to-install-and-secure-phpmyadmin-with-nginx-on-an-ubuntu-14-04-server

Cloud on I will use a site based on Wordpress.

Please, now what should I install to run the e-mail system of wordpress?

Example user @mydomain.com or if I want to use an external e-mail? Example miodominio@gmail.com?

Thank you so much! Grabriel