SMTP, which stands for Simple Mail Transfer Protocol, is the software that enables you to send out e-mail messages from your email addresses. Without it, you won't be able to use e-mail apps or webmail. Every time you send a message, your SMTP server creates a connection to a DNS server to determine exactly where e-mails for the recipient domain name are handled. After that, it connects to the remote email server and exchanges details. If the recipient mail box is accessible, your server transmits the email to the receiving POP/IMAP server and the latter delivers that email to the specific mailbox where the recipient can see it. If you'd like to be able to send e-mails, it is recommended to ensure that the website hosting company provides the service with their plans. Even if you work with an online form that website visitors use to make contact with you, you'll still require an active SMTP server for your hosting account for the web form to work.