SMTP, which is an acronym for Simple Mail Transfer Protocol, is the software that permits you to send out e-mails from your email addresses. Without this, you will not be able to employ e-mail applications or webmail. Once you send an e-mail, your SMTP server connects to a DNS server to discover where the e-mails for the recipient domain are handled. Then, it creates a connection to the remote email server and exchanges information. When the recipient mailbox is present, your server transmits the e-mail to the receiving POP/IMAP server and the latter delivers that email to the particular mailbox where the recipient can access it. If you would like to be able to send emails, it is recommended to make sure that the hosting company offers the service with their plans. Even when you make use of online form that website visitors use to get hold of you, you'll still require an active SMTP server for your hosting account for the web form to operate.