SMTP, which is an acronym for Simple Mail Transfer Protocol, is the software that enables you to send e-mails from your email addresses. Without it, you won't 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 where the e-mails for the recipient domain name are taken care of. Following that, it creates a connection to the remote email server and exchanges details. When the recipient mail box is present, your server transmits the message to the receiving POP/IMAP server and the latter brings that e-mail to the specific mailbox where the receiver can access it. If you would like to be able to send e-mails, you should always 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 still require an active SMTP server for your hosting account for the form to operate.