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 it, you won't be able to employ e-mail apps or webmail. After you send an e-mail, your SMTP server connects to a DNS server to determine exactly where e-mails for the recipient domain name are taken care of. Then, it creates a connection to the remote email server and trades details. When the recipient mail box is present, your server sends the e-mail to the receiving POP/IMAP server and the latter delivers that e-mail to the particular mailbox in which the receiver can get it. If you wish to send emails, it is recommended to ensure that the web hosting company offers the service with their packages. Even if you make use of online form that site visitors use to make contact with you, you'll still require an active SMTP server for your hosting account for the web form to function.