SMTP, which is an acronym for Simple Mail Transfer Protocol, is the software that permits you to send out e-mail messages from your email addresses. Without this, you will not be able to use email applications or webmail. When you send an email, your SMTP server creates a connection to a DNS server to determine where the e-mails for the recipient domain name are managed. After that, it connects to the remote email server and exchanges details. In case the recipient mailbox is accessible, your server sends the message to the receiving POP/IMAP server and the latter delivers that e-mail to the precise mailbox in which the recipient can see it. If you wish to be able to send emails, it is recommended to ensure that the hosting company provides the service with their packages. Even if 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.