SMTP, which stands for Simple Mail Transfer Protocol, is the software that allows you to send e-mails from your email addresses. Without it, you won't be able to use e-mail apps or webmail. When you send an e-mail, your SMTP server connects to a DNS server to determine exactly where emails for the recipient domain name are taken care of. Following that, it connects to the remote mail server and exchanges details. In case the recipient mailbox is available, your server transmits the e-mail to the receiving POP/IMAP server and the latter delivers that message to the precise mailbox in which the receiver can see it. If you'd like to be able to send emails, it is recommended to ensure that the hosting company offers the service with their plans. Even when you use an online form that website visitors use to get hold of you, you will still require an active SMTP server for your hosting account for the web form to work.