In case you have a website hosting plan and you set up an email address, you may take the option to send and receive messages for granted, but in fact, this is not always the case. Sending e-mails isn't always a part of the web hosting packages that providers will offer you and an SMTP service is necessary to be able to do that. The acronym means Simple Mail Transfer Protocol and that is the piece of software that permits you to send out emails. If you are using an e-mail application, it connects to the SMTP server. The latter then requests the DNS data of the domain, which is a part of the receiving address to find out what email server handles its e-mails. After some system data is swapped, your SMTP server delivers the message to the remote IMAP or POP server and then the email is finally delivered in the matching mailbox. An SMTP server is necessary if you are using some sort of contact page as well, so if you use a cost-free hosting plan, as an example, it's probable that you won't be able to make use of such a form as many free of charge web hosting providers don't allow outgoing email messages.