SMTP, which is an acronym for Simple Mail Transfer Protocol, is the software that enables you to send out e-mails from your email addresses. Without it, you won't be able to use email applications or webmail. Once you send an email, your SMTP server creates a connection to a DNS server to discover exactly where emails for the recipient domain name are managed. Then, it creates a connection to the remote email server and exchanges details. When the recipient mailbox exists, your server transmits the e-mail to the receiving POP/IMAP server and the latter brings that email to the particular mailbox where the recipient can get it. If you want to be able to send emails, it is recommended to make certain that the web hosting company offers the service with their packages. Even though you use an online form that visitors use to make contact with you, you still need an active SMTP server for your hosting account for the form to operate.