Email is not being delivered to certain external domains. This may be especially noted for emails sent to both internal/external recipients. The Exchange message tracking logs show the following:
First seen in
PureMessage for Microsoft Exchange 3.0.0
The Pickup and/or Replay directories in Exchange have incorrect permissions set for the “Network Service” user.
What To Do
First, check the Event Viewer for any errors associated with MSExchangeTransport, specifically with Event ID 9002:
The Network Service account doesn't have the necessary permissions assigned on the Pickup directory or Replay directory
The MSExchangeTransport Pickup process does not have the necessary "Read" permission and "Delete Subfolders and Files" permission for the pickup directory.
If either error appears, then follow the steps in the follow Microsoft Technet article to confirm that the appropriate permissions are correct: http://technet.microsoft.com/en-us/library/ff360668(v=exchg.140).aspx