SMTP, which is an acronym for Simple Mail Transfer Protocol, is the software that enables you to send e-mail messages from your email addresses. Without this, you won't be able to employ e-mail apps or webmail. Whenever you send a message, your SMTP server creates a connection to a DNS server to find out exactly where emails for the recipient domain are managed. Following that, it connects to the remote email server and trades information. When the recipient mail box is available, 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 access it. If you want to send e-mails, it is recommended to make sure that the website hosting company provides the service with their plans. Even if you work with an online form that site visitors use to contact you, you'll still need an active SMTP server for your hosting account for the form to function.