SMTP, which is short 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 email applications or webmail. Whenever you send a message, your SMTP server creates a connection to a DNS server to learn exactly where emails for the recipient domain are handled. Following that, it connects to the remote mail server and exchanges details. When the recipient mailbox is accessible, your server transmits the email to the receiving POP/IMAP server and the latter delivers that message to the specific mailbox where the recipient can see it. If you want to be able to send e-mails, you should always ensure that the hosting company provides the service with their plans. Even if you make use of online form that visitors use to make contact with you, you'll still need an active SMTP server for your hosting account for the web form to operate.