If you'd like to send e-mail messages using an e-mail address with your domain name, you have to make sure that the company will give you usage of their SMTP server. The latter is the software that enables e-mails to be sent. SMTP is an acronym for Simple Mail Transfer Protocol and it manages all outgoing emails from apps, webmail and contact forms. When a message is sent, the SMTP server checks with all the DNS servers worldwide where the e-mails for the receiving domain are handled and when it acquires this data, it connects to the remote POP/IMAP server to find out if the recipient mail box exists. When it does, the SMTP server sends the e-mail body and then the receiving server delivers it to the mailbox where the recipient can open it and see it. Without having a SMTP server on your end, you won't be able to send out e-mails in any way.