If you need an email address with the Code Rood domain you can request one (#tech-public channel on chat). We will send you a log in through an encrypted medium. To then access the mail box you can do the following things.
See this guide to configure Thunderbird (in Dutch). For English check here and then do this. For other programs check here.
Go to https://greenhost.net. In the upper right corner click “Login” and click “Webmail”.