SMTP, which is an acronym for Simple Mail Transfer Protocol, is the software that permits you to send e-mails from your email addresses. Without it, you will not be able to use e-mail apps or webmail. When you send an e-mail, your SMTP server connects to a DNS server to find out exactly where emails for the recipient domain name are managed. Then, it creates a connection to the remote email server and exchanges details. If the recipient mailbox is present, your server sends the e-mail to the receiving POP/IMAP server and the latter delivers that e-mail to the precise mailbox in which the recipient can get it. If you want to be able to send e-mails, it is best to ensure that the hosting company provides the service with their plans. Even though you work with an online form that site visitors use to get hold of you, you will still require an active SMTP server for your hosting account for the form to function.