This code indicates a general categorizer-based failure (bad address failure). A mail address or other attribute cannot be ...

{4}: This code indicates a general categorizer-based failure (bad address failure). A mail address or other attribute cannot be found in the directory. This issue may occur if contact entries do not have the 'targetAddress' attribute set. This issue occurs most frequently when the categorizer receives 'object not found' errors when trying to retrieve the 'homeMDB' property. Another possible cause is that the local 'System' account does not have sufficient permissions to read the 'homeMDB' attribute. Troubleshooting: Verify that the recipient address is formatted correctly and resend the message. Check permissions inheritance on the Exchange directory objects.