SMTP, which stands for Simple Mail Transfer Protocol, is the software that permits you to send e-mail messages from your email addresses. Without it, you won't be able to employ e-mail apps or webmail. Whenever you send a message, your SMTP server connects to a DNS server to find out where the emails for the recipient domain are handled. Subsequently, it creates a connection to the remote email server and exchanges details. In case the recipient mail box is accessible, your server transmits the email to the receiving POP/IMAP server and the latter delivers that e-mail to the particular mailbox in which the receiver can see it. If you would like to be able to send e-mails, you should always ensure that the web hosting company offers the service with their packages. Even though you use 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 operate.