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 use email apps or webmail. Whenever you send an email, your SMTP server creates a connection to a DNS server to learn exactly where emails for the recipient domain are taken care of. Following that, it creates a connection to the remote mail server and trades information. If the recipient mail box is available, your server transmits the e-mail to the receiving POP/IMAP server and the latter delivers that message to the specific mailbox in which the receiver can find it. If you would like to be able to send e-mails, you should always make sure that the website hosting company offers the service with their plans. Even if 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.