SMTP, which is an acronym for Simple Mail Transfer Protocol, is the software that enables you to send e-mail messages from your email addresses. Without this, you won't be able to use e-mail apps or webmail. When you send an email, your SMTP server connects to a DNS server to learn where the emails for the recipient domain name are handled. After that, it connects to the remote mail server and trades details. In case the recipient mail box is present, your server transmits the message to the receiving POP/IMAP server and the latter delivers that e-mail to the particular mailbox where the receiver can access it. If you'd like to send emails, it is recommended to make certain that the web hosting company has the service with their plans. Even though you make use of online form that site visitors use to contact you, you will still need an active SMTP server for your hosting account for the form to operate.