SMTP, which is an acronym for Simple Mail Transfer Protocol, is the software that allows you to send e-mails from your email addresses. Without it, you will not be able to employ e-mail apps or webmail. When you send an email, your SMTP server creates a connection to a DNS server to learn exactly where emails for the recipient domain name are handled. After that, it creates a connection to the remote mail server and trades details. If the recipient mailbox exists, your server sends the email to the receiving POP/IMAP server and the latter delivers that message to the specific mailbox where the recipient can find it. If you'd like to send emails, you should always make certain that the hosting company provides the service with their plans. 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.