An SMTP server is a server that allows you to send emails.
If you have your own domain name, your host probably allows you to use their SMTP to send emails.
Configure the SMTP server
Head over to Parameters > Configuration > Email.
Enter the following information:
Sender email: email that will be displayed as the sender of the contact emails.
Host: Outgoing server
Port: Outgoing Port (if the outgoing number doesn’t work, try entering the number 25)
User: Your email
Password: Your email password