SMTP, which is short for Simple Mail Transfer Protocol, is the software that permits you to send emails from your email addresses. Without it, you won't be able to employ e-mail applications or webmail. When you send an email, your SMTP server connects to a DNS server to determine where the e-mails for the recipient domain are handled. Following that, it creates a connection to the remote email server and trades information. In case the recipient mailbox is available, your server transmits the email to the receiving POP/IMAP server and the latter brings that message to the specific mailbox where the receiver can get it. If you would like to send emails, you should always ensure that the web hosting company provides the service with their packages. Even though you work with an online form that website visitors use to get hold of you, you'll still need an active SMTP server for your hosting account for the form to work.