SMTP, which is an acronym for Simple Mail Transfer Protocol, is the software that permits you to send emails from your email addresses. Without this, 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 learn where the e-mails for the recipient domain are taken care of. Following that, it creates a connection to the remote mail server and trades details. When the recipient mail box is accessible, your server sends the message to the receiving POP/IMAP server and the latter delivers that email to the specific mailbox in which the receiver can see it. If you want to send emails, you should always ensure that the website hosting company offers the service with their packages. Even though you work with an online form that site visitors use to get hold of you, you still need an active SMTP server for your hosting account for the form to work.