SMTP, which is short for Simple Mail Transfer Protocol, is the software that enables you to send out e-mails from your email addresses. Without this, you will not be able to employ email apps or webmail. Once you send an e-mail, your SMTP server creates a connection to a DNS server to determine exactly where emails for the recipient domain name are handled. Then, it connects to the remote email server and trades information. In case the recipient mail box is available, your server transmits the e-mail to the receiving POP/IMAP server and the latter delivers that e-mail to the specific mailbox in which the recipient can access it. If you want to be able to send emails, it is best to make sure that the website hosting company has the service with their packages. Even though you work with 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 web form to work.