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 it, you will not be able to use email apps or webmail. Whenever you send an email, your SMTP server creates a connection to a DNS server to discover exactly where e-mails for the recipient domain are managed. Following that, it creates a connection to the remote email server and exchanges details. In case the recipient mailbox is available, your server sends the email to the receiving POP/IMAP server and the latter brings that message to the specific mailbox in which the recipient can get it. If you would like to send e-mails, you should always make sure that the website hosting company has the service with their plans. Even if you make use of online form that website visitors use to get hold of you, you'll still require an active SMTP server for your hosting account for the web form to work.