The SMTP acronym stands for Simple Mail Transfer Protocol and this is the set of scripts that allows you to send out emails. If you work with an email application, it creates a connection to the SMTP server. The latter then searches the DNS data of the domain name, which is a part of the receiving address to find out what email server handles its emails. After system information is transferred, the SMTP server provides the email to the remote IMAP or POP server and then the email is finally delivered in the corresponding mailbox. An SMTP server is necessary if you are using a contact page form on your website too.