How the Outlook Sniffer Processes Your Appointments

Recently, a colleague contacted me and told me about a Microsoft Office Outlook problem that his customer was having. Here's what he wrote: "Do you know of any way to stop meeting requests from appearing in the Calendar as tentative before they are accepted?" I investigated this issue and found out that the process that handles this behavior is called the sniffer. I also discovered some interesting facts about how the sniffer works—as well as a workaround for my colleague's problem.

Let me start by explaining what the sniffer does. Whenever a meeting request arrives in your Inbox, the sniffer processes the item and places a "time blocker" in your calendar as a tentative appointment. For example, let's assume you receive an appointment request for next Thursday from 1 P.M. to 2 P.M. As soon as you read the appointment in your Inbox, that time slot is marked in your calendar as a tentative appointment. You don't need to accept or tentatively accept the appointment to add it to your calendar; the sniffer does this automatically.

The important difference between the sniffer's action and what happens when you accept an appointment as tentative is that the originator of the meeting doesn't receive any kind of response when the sniffer processes the appointment. Also, the sniffer doesn't process appointments automatically when they arrive: You either have to open the item or view it in the preview pane for it to be processed.

So, what's the practical purpose of the sniffer? Basically, it should keep you from missing any meetings you forget to respond to when they arrive. Thanks to the sniffer, these items automatically appear on your calendar, so you should see them and be able to consider them in your planning. When you delete an appointment request from your Inbox, the sniffer removes the automatically created appointment from your calendar. If you've meanwhile responded to the meeting organizer by accepting the meeting, the appointment of course isn't removed from your calendar.

The sniffer also helps you manage your appointments in the calendar: When you open an automatically added appointment in your calendar in Outlook 2007, it informs you that you haven't yet responded by including a "Please respond" message. Then, you can directly accept, tentatively accept, or decline the meeting, which of course sends a response to the meeting organizer with your decision.

The sniffer was implemented by Microsoft in Outlook 2000 and has been processing Outlook appointment requests ever since; it can't be turned off. The only workaround to prevent this behavior is to move appointment requests out of your Inbox before the sniffer can process them. You can do this by using the Rules Wizard. Follow these steps to create the rule:

  1. Create a folder where you want all new appointment requests to go; make sure the Reading pane is turned off on this folder.
  2. Select your Inbox, then select Tools, Rules and Alerts from the menu.
  3. Click New Rule to open the Rules Wizard.
  4. Select Check messages when they arrive, then click Next.
  5. On the Select conditions page, select which is a meeting invitation or update.
  6. On the next page, select move it to the specific folder and define the new folder you created as the target.
  7. Click Finish to create the rule.

With this rule, any incoming appointment request will be automatically moved to the folder you chose. You have to access this folder to respond to the request. Appointments will no longer automatically appear in your calendar. However, the sniffer works in all your folders, not only the Inbox. So, when you look at requests in the new folder, you should be prepared to respond immediately if you don’t want to see the tentative meeting on your calendar.

The sniffer is a very useful background process in Outlook that most people have probably never encountered before. I hope this column brought you some insights on what happens in the background whenever you receive an Outlook appointment.

This is my last column for the Exchange & Outlook UPDATE, Outlook Edition, due to changes that Windows IT Pro has decided to implement. I want to say good-bye, and I hope you have enjoyed my columns in the last (almost) two years. I've received some really interesting email messages from you, and I want to thank you for your very positive comments. You can expect some feature articles about Exchange Server and Outlook topics from me in the near future. Feel free to contact me with any questions about my columns at [email protected].

Sigi's Outlook Internet Site of the Month
This month's free Outlook tool is Easy2Add from 4Team Corporation. You use this tool to create appointments and tasks in Microsoft Office Outlook just by typing a sentence. For example, if you enter, "Lunch with Brian at 1pm," the tool creates a new appointment on your Outlook calendar with "Lunch with Brian" as the subject and sets the start time at 1 P.M. Isn't that neat? Easy2Add works with Windows 2000 or later and Outlook XP or later. You can download Easy2Add from 4Team Corporation's website. 

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.