SMTP, which is an acronym for Simple Mail Transfer Protocol, is the software that enables you to send out e-mail messages from your email addresses. Without this, you will not be able to use email applications or webmail. When you send an e-mail, your SMTP server connects to a DNS server to find out exactly where e-mails for the recipient domain name are taken care of. After that, it creates a connection to the remote email server and trades information. In case the recipient mail box is accessible, your server transmits the e-mail to the receiving POP/IMAP server and the latter delivers that email to the specific mailbox in which the recipient can find it. If you want to be able to send e-mails, it is recommended to ensure that the website hosting company has the service with their packages. Even though you use an online form that website visitors use to contact you, you will still require an active SMTP server for your hosting account for the web form to function.