When you have a web hosting package and you set up an email address, you might consider the option to send out and receive emails for granted, however, that isn't always the case. Sending emails isn't always a part of the web hosting packages that providers have and an SMTP service is necessary to be capable to do that. The acronym stands for Simple Mail Transfer Protocol and that is the piece of software that allows you to send out e-mail messages. If you use an e-mail program, it creates a connection to the SMTP server. The latter then queries the DNS data of the domain, which is a part of the receiving address to find out which email server manages its e-mails. After some system data is interchanged, your SMTP server delivers the email to the remote IMAP or POP server and the email is finally delivered in the matching mailbox. An SMTP server is required if you are using some sort of contact page form too, so if you have a free hosting plan, for instance, it is likely that you won't have the ability to use such a form since many no charge hosting providers do not allow outgoing emails.