If you would like to send email messages through an email address with your personal domain name, you have to make sure that the company will give you access to their SMTP server. The latter is the software system enabling emails to be sent out. SMTP is an acronym for Simple Mail Transfer Protocol and it manages all outbound emails from apps, webmail and contact forms. Whenever a message is sent out, the SMTP server checks with the DNS servers around the world where the emails for the receiving domain name are taken care of and when it obtains this info, it will connect into the remote POP/IMAP server to find out if the recipient mail box exists. In case it does, the SMTP server transmits the email body and so the receiving server sends it to the mailbox where the recipient can open it up and read it. With no SMTP server on your server, you won't be able to send messages at all.