SMTP, which is short for Simple Mail Transfer Protocol, is the software that enables you to send messages from your email addresses. Without this, you won't be able to employ email applications or webmail. Whenever you send an email, your SMTP server connects to a DNS server to find out where the e-mails for the recipient domain are taken care of. Following that, it creates a connection to the remote mail server and trades details. If the recipient mailbox is present, your server sends the email to the receiving POP/IMAP server and the latter brings that e-mail to the precise mailbox where the recipient can access it. If you want to send emails, it is recommended to make sure that the hosting company offers the service with their plans. Even if you make use of online form that visitors use to get hold of you, you'll still require an active SMTP server for your hosting account for the form to operate.