SMTP, which stands for Simple Mail Transfer Protocol, is the software that permits you to send out e-mail messages from your email addresses. Without this, you won't be able to employ e-mail applications or webmail. Whenever you send an email, your SMTP server connects to a DNS server to learn exactly where e-mails for the recipient domain are handled. Following that, it creates a connection to the remote mail server and trades details. If the recipient mailbox is available, your server sends the message to the receiving POP/IMAP server and the latter brings that e-mail to the particular mailbox where the receiver can see it. If you would like to send emails, it is best to make certain that the web hosting company has the service with their packages. Even if you use an online form that website visitors use to make contact with you, you'll still need an active SMTP server for your hosting account for the form to work.