Saturday, May 21, 2011

Insight into the Ignore Feature in Outlook 2010

In this blog post we will take an insight into how the Ignore feature in Outlook 2010 works. The Ignore feature excludes you from conversation threads your not interested in. If your new to the Ignore feature please read the following URL:

Where are Ignore rules stored?

Ignore rules are stored in the inside the users mailbox within a mailbox database. They are treated like an Outlook rule and stored in the XML blob. You can view these rules using MFCMAPI.

As an end user can I view a list of which conversations I'm ignoring?

As an end user using Outlook 2010 there is currently no way of viewing which conversations your ignoring.

As an Exchange Administrator you can use MFCMAPI to view within a mailbox which conversations are currently being ignored. In MFCMAPI under the users mailbox there is a "Conversation Action Settings" hidden folder. If you right click on this folder and click "View Associated Contents table" you can see all the ignored conversations. If you look at the MAPI property “PR_SUBJECT”, you will see the conversation subject string.

Is there a limit to the number of conversations you can ignore?

This is unknown however I have spoke to a senior esculation team within the Exchange product group and me mentioned he has seen over 100,000 before.

Does the client or server process ignored conversations?

The server does it.

What happens to emails that get ignored?

Ignored emails are moved to the deleted items folder within the Exchange 2010 mailbox dumpster. Exchange 2010 uses dumpster 2.0. For more information please see:

How long do ignores last for? For example if I do an ignore to a conversation thread then 6 months later someone does a reply to all on an unrelated topic, does this mean I will not recieve the email?

Ignore Rules only last for 180 days.

Do ignore rules use the message subject of an email?

No it uses the conversationID or conversationTopic properties generated by the Exchange 2010 server.

When you ignore a conversation thread does it include "re:" and "fw:"?

Not unless you’re using conversationTopic, in which case changing the subject will sometimes cause the message to escape. However, adding "re" or "fw" (or their localized equivalents) shouldn’t have any effect.

Hope this information has been helpful.


  1. Clint, is it possible to have the messages that tag to ignore go to a folder that I select instead of the Deleted Items folder?

    1. I was looking for a similar feature, ended up creating a Quick Step which applies a rule to the conversation (moves to a "Noise" folder). Seems like it does the trick just as easily.

  2. Not that I'm aware of, I have never done that before. If you find a solution please post back what it was.

  3. Clint,

    Does this apply to users using outlook 2010 and Exchange 2007 SP3? If so is the message stored in dumpster 1.0?



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  5. Clint,

    We have mandatory security tags at the end of our Subject lines, such as "[SEC=UNCLASSIFIED]". This causes replies to outside emails to be listed as a different conversation. Is there a way to get the server to ignore certain phrases when generating the conversationID or conversationTopic?
    Maybe by hooking into however it ignores "fw:" or "re:"?