SMTP, which is an acronym for Simple Mail Transfer Protocol, is the software that permits you to send out messages from your email addresses. Without this, you will not be able to employ email applications or webmail. After you send a message, your SMTP server creates a connection to a DNS server to find out exactly where emails for the recipient domain name are handled. Then, it connects to the remote mail server and exchanges details. In case the recipient mailbox is present, your server sends the e-mail to the receiving POP/IMAP server and the latter brings that message to the specific mailbox where the receiver can find it. If you wish to send emails, it is best to make certain that the hosting company has the service with their packages. Even when you make use of online form that website visitors use to contact you, you'll still need an active SMTP server for your hosting account for the form to work.