We recommand to use a recent version of thunderbird, as it recognizes our mailserver automatically.
To create a HaDiKo-mailaccount, go to File->New->Mail Account... in the menu and fill the following form. As mailaddress choose any of your aliases.
Now thunderbird should detect our mailserver automatically. The username was told you by the HaDiNet and may not be the same as in your mailaddress.
In case the mailserver was not detected automatically, activate SSL/TLS-Encryption and switch the port to 993.
If you encounter problems sending mails, check the settings of the mail server. Here is a working configuration: