In case you have a cloud hosting account and you set up an email address, you may consider the option to send out and receive messages for granted, however, that isn't always true. Sending emails isn't necessarily part of the web hosting plans that companies have and an SMTP service is needed to be capable to do that. The abbreviation means Simple Mail Transfer Protocol and that is the piece of software that allows you to send out e-mails. If you work with an e-mail application, it connects to the SMTP server. The latter then requests the DNS data of the domain name, that is a part of the receiving address to find out which mail server manages its emails. After some system information is interchanged, your SMTP server delivers the message to the remote IMAP or POP server and the e-mail is finally delivered in the matching mailbox. An SMTP server is necessary if you work with some kind of contact page form too, so if you use a free hosting plan, for example, it is very likely that you will not have the ability to make use of such a form since many no charge hosting service providers don't allow outgoing emails.