If you need to send out emails using an email address with your own domain, you have to make sure that the company will provide you with access to their SMTP server. The latter is the software that allows e-mail messages to be transmitted. SMTP is an abbreviation for Simple Mail Transfer Protocol and it addresses all outgoing email messages from programs, webmail and contact web forms. Whenever a message is sent, the SMTP server confirms with all of the DNS servers worldwide where the emails for the receiving domain are taken care of and as soon as it gets this data, it will connect into the remote POP/IMAP server to check if the recipient mail box exists. In case it does, the SMTP server sends the email body and so the receiving server sends it to the mail box in which the recipient can open it and see it. Without having a SMTP server on your end, you won't be capable to mail out messages at all.