If you want to send out email messages using an e-mail address with your domain name, you have to make sure that the company will give you usage of their SMTP server. The latter is the software system which permits email messages to be dispatched. SMTP is an abbreviation for Simple Mail Transfer Protocol and it deals with all outbound e-mails from applications, webmail and contact web forms. Every time a message is sent out, the SMTP server confirms with all the DNS servers around the world where the e-mails for the receiving domain name are handled and as soon as it gets this information, it creates a connection into the remote POP/IMAP server to check if the recipient mailbox is available. In case it does, the SMTP server transmits the email body while the receiving server sends it to the mailbox in which the recipient can open it and read it. With no SMTP server on your end, you won't be able to mail out e-mails in any way.