Received email address shows username-domain<username@domain> instead of username@domain

I, everything is up and running. I have set virtualmin to setup usernames in the username@domain format. However, when I send an email to gmail, it still shows username-domain <username@domain> when email is received. So instead of my name showing it shows username-domain. (the "-" is bothering me") I would be ok if it showed username@domain. Is there any way to change this. I assume it's a setting in the email header somewhere.

When I view the email source:

MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Wed, 27 Jul 2016 17:07:18 +0200 From: "username-domain" <username@domain> To: xxx@gmail.com Subject: testing Message-ID: 6827cbd8e6ed4feba865fd4e8e17aa3e@roberthansen.co.za X-Sender: username@domain User-Agent: Roundcube Webmail/1.2.0

Thanks.