In order for you to send out e-mail messages using an email address with your own domain name, make sure that the company will provide you with usage of their SMTP server. The latter is the software enabling emails to be sent out. SMTP is an abbreviation for Simple Mail Transfer Protocol and it deals with all outbound emails from applications, webmail and contact forms. When a message is sent, the SMTP server confirms with all of the DNS servers globally where the e-mails for the receiving domain are managed and as soon as it gets this information, it will connect to the remote POP/IMAP server to find out if the recipient mailbox exists. When it does, the SMTP server delivers the e-mail body and so the receiving server sends it to the mail box where the recipient can open it and see it. Without having a SMTP server on your server, you will not be capable to send emails at all.