SMTP, which stands for Simple Mail Transfer Protocol, is the software that permits you to send out messages from your email addresses. Without this, you won't be able to use e-mail apps or webmail. Every time you send an email, your SMTP server connects to a DNS server to discover exactly where e-mails for the recipient domain name are taken care of. After that, it creates a connection to the remote email server and trades information. If the recipient mailbox exists, your server sends the email to the receiving POP/IMAP server and the latter brings that email to the precise mailbox in which the receiver can see it. If you'd like to be able to send emails, it is best to ensure that the hosting company has the service with their packages. Even if you make use of online form that site visitors use to contact you, you'll still need an active SMTP server for your hosting account for the web form to operate.