In case you have a cloud hosting plan and you create an email address, you might take the option to send and receive messages for granted, but in fact, this isn't always true. Sending emails is not always a part of the hosting packages that companies offer and an SMTP service is required to be capable to do that. The abbreviation means Simple Mail Transfer Protocol and that is the piece of software that permits you to send emails. If you use an e-mail app, it creates a connection to the SMTP server. The latter then queries the DNS records of the domain, which is a part of the receiving address to find out which mail server deals with its email messages. After some system data is swapped, your SMTP server provides the email to the remote IMAP or POP server and then the e-mail is finally delivered in the related mailbox. An SMTP server is needed if you are using some kind of contact page form too, so in case you use a free hosting plan, for instance, it is likely that you won't be able to make use of such a form as many no charge hosting companies do not allow outgoing email messages.