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 employ email apps or webmail. When you send an e-mail, your SMTP server creates a connection to a DNS server to find out exactly where emails for the recipient domain name are managed. Subsequently, it creates a connection to the remote mail server and exchanges details. In case the recipient mailbox is available, your server transmits the e-mail to the receiving POP/IMAP server and the latter delivers that email to the particular mailbox in which the receiver can access it. If you wish to send emails, you should always make certain that the hosting company offers the service with their packages. Even if you use an online form that site visitors use to contact you, you will still require an active SMTP server for your hosting account for the web form to work.