SMTP, which is short for Simple Mail Transfer Protocol, is the software that allows you to send out e-mails from your email addresses. Without it, you will not be able to use e-mail apps or webmail. Every time you send an email, your SMTP server creates a connection to a DNS server to discover where the emails for the recipient domain are managed. Subsequently, it creates a connection to the remote email server and trades information. When the recipient mail box exists, your server transmits the message to the receiving POP/IMAP server and the latter delivers that email to the particular mailbox where the recipient can access it. If you wish to be able to send emails, it is recommended to make certain that the hosting company offers the service with their plans. Even though you work with 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 operate.