SMTP, which is short for Simple Mail Transfer Protocol, is the software that permits you to send out e-mail messages from your email addresses. Without it, you will not be able to employ e-mail applications or webmail. When you send a message, your SMTP server connects to a DNS server to learn exactly where emails for the recipient domain name are handled. Then, it creates a connection to the remote mail server and trades information. In case the recipient mailbox is accessible, your server transmits the email to the receiving POP/IMAP server and the latter brings that e-mail to the specific mailbox in which the recipient can find it. If you'd like to be able to send e-mails, it is best to make sure that the website hosting company offers the service with their plans. Even though you work with an online form that website visitors use to make contact with you, you'll still require an active SMTP server for your hosting account for the form to operate.