If you want to send emails through an email address with your own domain, you have to make sure that the company will provide you with usage of their SMTP server. The latter is the software which permits email messages to be dispatched. SMTP is an abbreviation for Simple Mail Transfer Protocol and it handles all outbound e-mails from applications, webmail and contact forms. Every time a message is sent out, the SMTP server confirms with all the DNS servers worldwide where the e-mails for the receiving domain are taken care of and when it gets this info, it connects to the remote POP/IMAP server to check if the recipient mail box is available. When it does, the SMTP server sends the message body and then the receiving server sends it to the mail box in which the recipient can open it and see it. Without an SMTP server on your end, you won't be capable to mail out e-mails at all.