SMTP, which is an acronym for Simple Mail Transfer Protocol, is the software that permits you to send out e-mails from your email addresses. Without it, you won't be able to use email applications or webmail. Every time you send a message, your SMTP server connects to a DNS server to discover exactly where emails for the recipient domain name are managed. Subsequently, it connects to the remote email server and trades information. If the recipient mailbox is available, your server sends the email to the receiving POP/IMAP server and the latter delivers that email to the precise mailbox where the receiver can see it. If you'd like to be able to send emails, you should always make certain that the website hosting company offers the service with their plans. Even though you work with an online form that site visitors use to get hold of you, you'll still need an active SMTP server for your hosting account for the form to work.