When you try to use Microsoft Office Outlook 2007 to send or save an e-mail message that was created in Microsoft Office OneNote 2007, you may encounter the following symptoms:
When you click Send to send the e-mail message, you receive the following message:
Cannot send this item.
When you click Save to save the e-mail message, you receive the following message:
The messaging interface has returned an unknown error. If the problem persists, restart Outlook.
Outlook 2007 crashes, and you receive the following message:
Cannot display the Folder. 'Microsoft Office OneNote' exited without properly closing your Outlook data File "Path to ost". 'Microsoft Office Outlook' must be restarted. If this error message recurs, contact support for Microsoft Office OneNote for assistance.
These symptoms occur when you create a file, send it to Mail Recipient, and then exit OneNote 2007.
To work around this issue, keep OneNote 2007 open when you send or save the e-mail message in Outlook 2007.