In order for you to send out e-mails using an e-mail address with your domain name, make sure that the company will give you access to their SMTP server. The latter is the software system which permits emails to be sent out. SMTP is an acronym for Simple Mail Transfer Protocol and it deals with all outbound e-mails from apps, webmail and contact web forms. Every time a message is sent, the SMTP server checks with all the DNS servers throughout the world where the emails for the receiving domain are taken care of and as soon as it gets this info, it connects to the remote POP/IMAP server to check if the recipient mailbox exists. In case it does, the SMTP server sends the e-mail body while the receiving server sends it to the mail box where the recipient can open it up and read it. Without an SMTP server on your server, you will not be capable to mail out e-mails at all.