Scenario: If you have a normal Exchange user mailbox that is not a resource, you can configure Outlook to process the meeting request automatically. To do so, perform the following within Outlook:
Click on File–>Options
1. Navigate to Mail–>Tracking. Make sure there is a check mark in Automatically process meeting requests and responses to meeting requests and polls.
2. Navigate to Calendar–>Automatic accept or decline. From here you can select from the menu how you wish to automatically process meeting requests:
- Automatically accept meeting requests and remove canceled meetings
- Automatically decline meeting requests that conflict with an existing appointment or meeting
- Automatically decline recurring meeting requests
Outlook uses a sniffer that is an idle process to process meeting requests. Only one machine can process sniffer requests. It only runs when Outlook is idle — if its never idle it will never run.
Troubleshooting:
1. Disable Outlook Addin’s and try again.
2. Use the /sniff or the /cleansniff when opening outlook.
3. Check the property PR_Processed with MFCMAPI on the mail message.
Ex-Shell 