SMTP, which is short for Simple Mail Transfer Protocol, is the software that allows you to send e-mail messages from your email addresses. Without this, you won't be able to use e-mail applications or webmail. Once you send a message, your SMTP server connects to a DNS server to determine where the e-mails for the recipient domain are taken care of. Subsequently, it creates a connection to the remote email server and exchanges details. If the recipient mail box is present, your server sends the email to the receiving POP/IMAP server and the latter brings that message to the precise mailbox in which the recipient can access it. If you would like to send e-mails, it is recommended to ensure that the web hosting company has the service with their packages. Even though you make use of online form that visitors use to get hold of you, you'll still need an active SMTP server for your hosting account for the web form to function.