Was ich aktuell gefunden habe wäre folgendes ( Sehr viel manueller Aufwand, aber wenns funktioniert wäre alles gut 
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Gibt es da charmantere Methoden?
Method for manually transferring Thunderbird MSF to Outlook
Before beginning the manual conversion process, the user must first install a Thunderbird plug-in, namely import/export tools.
- Launch the Thunderbird email client.
- Open the required folder to export in Outlook.
- Press Ctrl+A to pick all messages from this folder.
- Right-click on the emails you want to save and choose Save As option.
- To import MSF files into Outlook, go to the appropriate folder and save the files in the destination folder.
- Now open Microsoft Outlook and create a new folder to sort the converted emails into it.
- Enter the desired name, such as Thunderbird to PST, and simply click on OK.
- Now visit the Thunderbird emails location and select all emails and drag them to the new folder in MS Outlook.
- After this, all Thunderbird emails can be viewed in MS Outlook.