You access the Outlook Object Model (OOM). To do this, you use a custom Microsoft Outlook 2010 add-in, a custom script, or other programming language to read the DisplayType property of a Recipient object of an email message that is being replied to.
The add-in uses the following object properties to access the recipient's DisplayType:
In this scenario, you receive the following error:
Run-time error '-1040973553 (c1f4010f) The attempted operation failed. An object could not be found.
This issue occurs because the property PR_RECIPIENT_TYPE is not set when an email message is replied to. Earlier Outlook versions ignore the fact that the property is not set when the property is read. Outlook 2010 does not ignore this property. Therefore, you receive the error message that is mentioned in the "Symptoms" section.
To resolve this issue, you have to access the following DisplayType property of the AddressEntry object: