SMTP, which is an acronym for Simple Mail Transfer Protocol, is the software that permits you to send e-mail messages from your email addresses. Without this, you won't be able to employ e-mail applications or webmail. Once you send a message, your SMTP server creates a connection to a DNS server to learn where the e-mails for the recipient domain name are taken care of. Then, it connects to the remote email server and trades information. When the recipient mail box is present, your server transmits the message to the receiving POP/IMAP server and the latter brings that email to the specific mailbox in which the receiver can access it. If you would like to be able to send emails, you should always make sure that the web hosting company provides the service with their packages. Even when you work with an online form that visitors use to get hold of you, you'll still need an active SMTP server for your hosting account for the form to work.