If you'd like to send emails through an email address with your domain, you have to make sure that the company will give you usage of their SMTP server. The aforementioned is the software system which enables e-mails to be sent out. SMTP is an abbreviation for Simple Mail Transfer Protocol and it addresses all outbound emails from apps, webmail and contact forms. Whenever a message is sent, the SMTP server checks with all the DNS servers throughout the world where the e-mails for the receiving domain are handled and as soon as it obtains this info, it connects to the remote POP/IMAP server to see if the recipient mailbox exists. If it does, the SMTP server sends the message body and then the receiving server sends it to the mailbox in which the recipient can open it up and read it. Without having a SMTP server on your server, you won't be allowed to send out emails in any way.