SMTP, which is short for Simple Mail Transfer Protocol, is the software that allows you to send out e-mails from your email addresses. Without it, you will not be able to employ e-mail apps or webmail. Every time you send a message, your SMTP server connects to a DNS server to determine exactly where emails for the recipient domain are taken care of. Subsequently, it creates a connection to the remote email server and trades information. When the recipient mailbox is available, your server transmits the message to the receiving POP/IMAP server and the latter delivers that email to the precise mailbox where the receiver can see it. If you'd like to send emails, you should always make certain that the web hosting company has the service with their plans. Even when you make use of online form that visitors use to contact you, you will still require an active SMTP server for your hosting account for the form to function.