There are two different goals, between the question (How can I find “Ignored” messages in MS Outlook?) and the description (search criteria that can be used to find all messages/ conversations that have been marked to be ignored) of the question.
The Op answered and accepted their own answer for the search criteria, but also mentioned it would be useful to be able to periodically review something. This brings it back to the question.
After clicking "ignore" by accident, I had the same question. I found my answer here:
https://support.microsoft.com/en-us/help/2697913/messages-in-an-e-mail-thread-are-automatically-moved-to-the-deleted-it
This answers the question "How can I find “Ignored” messages in MS Outlook?", with something that one could "periodically review".
From the page (which has screenshots if needed):
To resolve this problem, remove the "ignore" status of the e-mail
thread using the following steps:
- Select your Deleted Items folder.
- Select the message that is currently set to be ignored by Outlook.
- Click Ignore on the Delete section of the Home tab on the ribbon.
- If prompted, click Stop Ignoring Conversation.
Note You can determine if a message is being ignored by the status of
the Ignore control on the ribbon. If the Ignore control is
highlighted, as shown in the following figures, the conversation
thread on that message is currently being ignored by Outlook.
I tested these steps myself, and found them to do exactly as claimed, which helped me solve my problem. I am writing this answer here, to answer the primary question asked.
Find the item in deleted items, select it and click the “Ignore” button again. This will 'un-ignore' the thread. I don't think there's a way to list all the ignored conversations, but you can definitely 'un-ignore' a conversation. – zain.ali – 2015-08-12T11:19:09.203
I am aware of the un-ignoring process. I was hoping to find a way to finding all ignored conversations. Unfortunately I am rapidly coming to the conclusion - that you can't. Just thought I should check with the wider community before I resigned to the fact. Thanks though. – Mskadu – 2015-08-12T11:33:42.410
Before you conclude, look at the last paragraph of this article. http://www.techrepublic.com/blog/microsoft-office/ignore-unwanted-email-conversations-in-outlook/
– zain.ali – 2015-08-12T11:39:32.687"Unfortunately, there's no way for you, the end user, to view a list of ignored conversations. It's just up to you to remember that you've ignored a conversation." - don't really want to go to a Exchange Admin every time, asking for that list. So quite clearly this is not possible. Thanks though. – Mskadu – 2015-08-12T13:05:11.490