SMTP, which is an acronym for Simple Mail Transfer Protocol, is the software that enables you to send out messages from your email addresses. Without it, you won't be able to employ email apps or webmail. Every time you send an email, your SMTP server creates a connection to a DNS server to learn where the e-mails for the recipient domain name are taken care of. Following that, it connects to the remote mail server and exchanges information. When the recipient mailbox is present, your server transmits the email to the receiving POP/IMAP server and the latter brings that message to the precise mailbox where the recipient can get it. If you want to send emails, you should always make sure that the web hosting company provides the service with their packages. Even when you work with an online form that website visitors use to make contact with you, you will still require an active SMTP server for your hosting account for the web form to work.