SMTP, which is an acronym for Simple Mail Transfer Protocol, is the software that allows you to send e-mail messages from your email addresses. Without it, you won't be able to employ e-mail apps or webmail. After you send a message, your SMTP server creates a connection to a DNS server to find out exactly where emails for the recipient domain are taken care of. Then, it creates a connection to the remote mail server and exchanges information. In case the recipient mail box is present, your server transmits the message to the receiving POP/IMAP server and the latter brings that e-mail to the precise mailbox where the recipient can access it. If you'd like to be able to send emails, you should always ensure that the hosting company provides the service with their plans. Even when you use an online form that website visitors use to get hold of you, you will still need an active SMTP server for your hosting account for the form to function.