SMTP, which is short for Simple Mail Transfer Protocol, is the software that enables you to send e-mails from your email addresses. Without it, you will not be able to use e-mail apps or webmail. After you send an email, your SMTP server creates a connection to a DNS server to learn where the e-mails for the recipient domain name are managed. Following that, it connects to the remote mail server and exchanges information. When the recipient mail box exists, your server sends the email to the receiving POP/IMAP server and the latter brings that message to the precise mailbox in which the recipient can find it. If you want to be able to send emails, it is best to ensure that the website hosting company has the service with their packages. Even when you use an online form that website visitors use to get hold of you, you'll still require an active SMTP server for your hosting account for the form to work.