If you'd like to send out emails using an e-mail address with your personal domain name, you have to make sure that the company will give you usage of their SMTP server. The latter is the software system allowing e-mails to be sent. SMTP is an abbreviation for Simple Mail Transfer Protocol and it deals with all outgoing e-mails from apps, webmail and contact web forms. Whenever a message is sent, the SMTP server confirms with the DNS servers globally where the emails for the receiving domain are managed and when it gets this data, it creates a connection into the remote POP/IMAP server to check if the recipient mail box is available. In case it does, the SMTP server directs the e-mail body and then the receiving server sends it to the mail box where the recipient can open it and see it. With no SMTP server on your server, you won't be capable to send messages at all.