SMTP, which stands for Simple Mail Transfer Protocol, is the software that permits you to send e-mails from your email addresses. Without it, you will not be able to use email applications or webmail. After 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. Subsequently, it creates a connection to the remote email server and trades information. In case the recipient mail box is present, your server transmits the email to the receiving POP/IMAP server and the latter brings that e-mail to the precise mailbox where the recipient can access it. If you would like to be able to send e-mails, it is recommended to ensure that the website hosting company has the service with their plans. Even when you use an online form that visitors use to make contact with you, you'll still require an active SMTP server for your hosting account for the web form to operate.