Moin,
2 von mir schon durchgeführte Wege waren:
1)
Alte ID mit dem neuen Certifier zertifiziert. Mußt dann halt den Schlüssel von der ID im Pers. Dokument ersetzen.
2) wie blizzard schon erwähnte:
How to recreate a user ID file
Technote (FAQ)
Problem
You have a user who has lost the ID file or password. You don't know how to recover a backup of the file. You decide to re-create the ID file for the user.
Note: Re-creating a user's ID file should only be considered as a last resort. If the user ID file must be recreated, you should make the user aware that any documents or database previously encrypted will be inaccessible after the new ID is created.
Solution
In order to recreate a user ID file, register the user to create the new file using the following steps:
1. Delete the current person document for the user using the Delete key on the keyboard, not the Delete User option in the Administrator client. If the Delete User option is used, the Administration Process will delete the user, removing the user from your Domino domain. This can cause considerable problems when you try to re-register the user and create the new ID file.
2. After the Person Document has been successfully deleted, select the Register User option in the People and Groups Tab.
3. When registering the user, ensure that you use the identical name previously registered for this user. In the Mail File section of the Registration Dialog box, choose a file name different from the mail file name previously used. Using the Set ID File option, place the ID file in a location that you can access later.
4. After the user has been successfully registered, edit the Person document to reflect the correct mail file (the user's older mail file). To do this, open the Person document and go to the Mail section of the Basics tab. Enter the older mail file name in the Mail File field.
5. Save and close the document.
Any cross certificates which the user had in his previous Person document or Personal Address Book must be recreated.
In beiden Fällen kommst Du nicht mehr an verschlüsselte Mails