In order for you to send out email messages through an email address with your personal domain, you have to make sure that the provider will give you usage of their SMTP server. The latter is the software system which allows emails to be sent. SMTP is an acronym for Simple Mail Transfer Protocol and it handles all outgoing emails from apps, webmail and contact forms. Every time a message is sent out, the SMTP server confirms with all of the DNS servers globally where the emails for the receiving domain name are managed and as soon as it gets this info, it will connect into the remote POP/IMAP server to see if the recipient mailbox is available. In case it does, the SMTP server directs the message body while the receiving server sends it to the mailbox in which the recipient can open it and see it. With no SMTP server on your server, you won't be capable to send e-mails at all.