In Microsoft Office Outlook 2007, you receive the following error message:
Microsoft Office Outlook had problems encrypting this message because the following recipients had missing or invalid certificates, or conflicting or unsupported encryption capabilities.
You receive this error message in the following scenarios:
Scenario 1 You have an external partner with an invalid or expired certificate in AutoComplete. This partner is not in other locations or address books. Then, you send an encrypted e-mail message and select this partner from AutoComplete.
Scenario 2 Office Outlook 2007 is configured to work offline. Therefore, address books are not available. In this case, you send an encrypted e-mail message and select a name from AutoComplete.
Note AutoComplete is a feature that displays suggestions for names and for e-mail addresses as you start to type them.
To resolve this problem, apply the following hotfix package:
978401 Description of the Office Outlook 2007 hotfix package (Outlook-x-none.msp): February 23, 2010
Workaround for scenario 1 Add the partner to the Contacts list. To do this, follow these steps:
On the Tools menu, click Address Book.
In the Address Book dialog box, select Global Address List in the Address Book list.
Type the partner name in the Search field, and then select the correct entry from the results.
On the File menu, click Add to Contacts.
Workaround for scenario 2 Make address books available offline or connect to the local area network (LAN).
To make address books available offline, click the drop-down arrow next to Send/Receive, and then click Download Address Book.