SMTP, which is short for Simple Mail Transfer Protocol, is the software that permits you to send out e-mails from your email addresses. Without it, you will not be able to use e-mail apps or webmail. When you send an e-mail, your SMTP server creates a connection to a DNS server to learn where the e-mails for the recipient domain are taken care of. Following that, it creates a connection to the remote mail server and exchanges details. When the recipient mailbox exists, your server sends the message to the receiving POP/IMAP server and the latter brings that e-mail to the specific mailbox where the recipient can get it. If you wish to send emails, it is best to make sure that the website hosting company offers the service with their plans. Even though you work with an online form that visitors use to make contact with you, you'll still need an active SMTP server for your hosting account for the web form to operate.