SMTP, which is short for Simple Mail Transfer Protocol, is the software that allows you to send e-mails from your email addresses. Without this, you will not be able to employ e-mail applications or webmail. Once you send an email, your SMTP server creates a connection to a DNS server to determine where the emails for the recipient domain name are managed. Subsequently, it connects to the remote email server and exchanges details. When the recipient mailbox is accessible, your server transmits the message to the receiving POP/IMAP server and the latter delivers that e-mail to the precise mailbox in which the receiver can find it. If you want to send e-mails, it is recommended to make sure that the web hosting company has the service with their plans. Even if you work with an online form that website visitors use to contact you, you still require an active SMTP server for your hosting account for the web form to work.