SMTP, which is short for Simple Mail Transfer Protocol, is the software that allows you to send out messages from your email addresses. Without this, you will not be able to employ e-mail apps or webmail. Whenever you send an e-mail, your SMTP server creates a connection to a DNS server to find out where the emails for the recipient domain name are managed. Subsequently, it creates a connection to the remote mail server and trades information. When the recipient mailbox is present, your server transmits the e-mail 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'd like to send emails, it is recommended to make sure that the web hosting company has the service with their packages. Even when you make use of online form that visitors use to get hold of you, you still require an active SMTP server for your hosting account for the form to function.