To use the application Thunderbird for sending E-Mails automatically at WinMOS300-Callback you need to configure Thunderbird as the default E-Mail application on your PC.
Open the main window by clicking the right mouse button on the name of your mailbox and select "Settings..." to configure it as default.
Then a new window opened called Account Settings. Please select Account Actions and then Set as Default if there is only one E-Mail account defined.
You need to configure your Outgoing Server additionally as default. Therefore please select Outgoing Server and then Set as Default.
Now E-Mails are sending with Thunderbird.