SMTP, which is an acronym for Simple Mail Transfer Protocol, is the software that allows you to send messages from your email addresses. Without it, you won't be able to employ e-mail apps or webmail. Whenever you send a message, your SMTP server connects to a DNS server to find out where the e-mails for the recipient domain name are handled. After that, it creates a connection to the remote mail server and exchanges details. If the recipient mail box exists, your server sends the message to the receiving POP/IMAP server and the latter delivers that e-mail to the particular mailbox where the recipient can see it. If you'd like to be able to send emails, it is recommended to ensure that the website hosting company offers the service with their packages. Even when you make use of online form that visitors use to contact you, you will still need an active SMTP server for your hosting account for the form to function.