SMTP, which is an acronym for Simple Mail Transfer Protocol, is the software that allows you to send out e-mail messages from your email addresses. Without it, you won't be able to employ email applications or webmail. When you send an e-mail, your SMTP server connects to a DNS server to discover exactly where emails for the recipient domain are handled. Following that, it connects to the remote email server and trades details. If the recipient mailbox is available, your server transmits the email to the receiving POP/IMAP server and the latter delivers that email to the precise mailbox in which the recipient can find it. If you wish to be able to send emails, it is recommended to make sure 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'll still need an active SMTP server for your hosting account for the web form to function.