SMTP, which is short for Simple Mail Transfer Protocol, is the software that allows you to send out e-mail messages from your email addresses. Without this, you won't be able to employ email apps or webmail. Once you send an e-mail, your SMTP server creates a connection to a DNS server to discover exactly where emails for the recipient domain are handled. Following that, it connects to the remote mail server and trades details. If the recipient mailbox is accessible, your server transmits the e-mail to the receiving POP/IMAP server and the latter delivers that e-mail to the precise mailbox in which the recipient can find it. If you want to be able to send emails, you should always make sure that the website hosting company provides the service with their packages. Even if you work with an online form that website visitors use to contact you, you still need an active SMTP server for your hosting account for the web form to work.