SMTP, which stands for Simple Mail Transfer Protocol, is the software that permits you to send out e-mails from your email addresses. Without this, you will not be able to employ e-mail apps or webmail. Once you send a message, your SMTP server connects to a DNS server to determine where the e-mails for the recipient domain are taken care of. Subsequently, it creates a connection to the remote mail server and trades details. If the recipient mail box is accessible, your server sends the message to the receiving POP/IMAP server and the latter brings that message to the particular mailbox in which the receiver can access it. If you would like to send e-mails, you should always make certain that the hosting company has the service with their packages. Even when you use an online form that visitors use to make contact with you, you will still need an active SMTP server for your hosting account for the web form to function.