When you tag emails, contacts, or calendar events with multiple categories in Outlook, finding items that match all those categories at once is not obvious. The standard search bar treats multiple category names as an OR condition, returning items that have any of the specified tags. To narrow results to items that contain every category you list, you need the category:= operator. This article explains how the operator works, shows step-by-step instructions for using it, and covers common pitfalls that cause incorrect search results.
Key Takeaways: Using category:= to Find Multi-Tagged Items
- category:= operator with comma-separated names: Returns only items that have all the listed categories assigned, acting as an AND filter.
- Instant Search bar in Outlook: Type category:= “Red Category”, “Blue Category” to find items tagged with both Red and Blue.
- Quotation marks around multi-word category names: Required when a category name contains spaces; otherwise the operator fails silently.
How the category:= Operator Works in Outlook Search
Outlook uses a query syntax that supports property-specific operators. The category property refers to the list of color categories assigned to an item. When you type category:= followed by one or more category names, Outlook interprets the list as an AND condition. Each category name must be present on the item for it to appear in the results.
Without the colon and equals sign, a plain category: query treats multiple names as an OR condition. For example, category:Red category:Blue returns items that have Red OR Blue. The category:= operator changes the logic so that only items with both Red AND Blue are shown.
This operator works in Outlook for Microsoft 365, Outlook 2021, Outlook 2019, and Outlook 2016. It works in the main mailbox, archive folders, and public folders. It does not work in Outlook on the web or Outlook for Mac, where the search syntax is different.
Prerequisites for Using the Operator
Before you use category:=, make sure the following are true:
- Categories are created and assigned to items using the Categorize button on the Home ribbon.
- You know the exact names of the categories as they appear in the category list. The operator is case-insensitive, but spelling must match.
- Instant Search is enabled. Go to File > Options > Search and verify that Instant Search is turned on.
Steps to Use the category:= Operator in Outlook Search
- Open the folder you want to search
Click the folder where the multi-tagged items are stored. For email, click your Inbox or a subfolder. For calendar, click Calendar in the navigation pane. - Click in the Instant Search box
The search box is at the top of the folder pane. Press Ctrl+E to jump directly to it. - Clear any previous search text
Press Escape or click the X icon inside the search box to remove old queries. - Type the operator and category names
Enter: category:= “Category A”, “Category B”
Replace Category A and Category B with your actual category names. Use double quotation marks around any name that contains spaces. Separate multiple names with a comma and a space. - Press Enter to run the search
Outlook filters the folder and displays only items that have every category you listed. The search bar shows the query you typed. - Refine the results if needed
Add more category names to narrow further. Remove a category to broaden the results. You can also combine category:= with other operators like from: or subject: using the standard query syntax.
Example Queries
The following examples show real-world uses of the operator:
- category:= “Client”, “Urgent” — finds items tagged with both Client and Urgent.
- category:= “Project Alpha”, “FY2024” — finds items tagged with Project Alpha and FY2024.
- category:= “Red Category” — finds items tagged with the Red Category only. This works the same as category:”Red Category” because only one name is specified.
Common Mistakes When Using the category:= Operator
Outlook Returns No Results Even Though Items Have the Categories
The most common cause is a spelling mismatch. Open the category list by clicking Categorize > All Categories and verify the exact spelling of each category name. Another cause is using the wrong punctuation. The operator requires a colon followed by an equals sign with no space between them. category: = with a space does not work.
Outlook Returns Items That Have Only One of the Categories
This happens when you omit the colon before the equals sign. Typing category=”Red”, “Blue” without the colon runs a plain text search, not a property search. Always type category:= as a single token.
Category Names with Spaces Are Ignored
If a category name contains a space and you do not wrap it in double quotation marks, Outlook treats the space as a separator between two different search terms. For example, category:=Red Category searches for the word Red and the word Category separately, not the category named Red Category. Always use quotation marks around any name that includes spaces.
Outlook Does Not Recognize the Operator in Certain Folders
The category:= operator works in folders that support Instant Search. It does not work in search folders created by the Search Folders feature unless the search folder is configured to use the same query syntax. It also does not work in shared mailboxes that are opened as additional mailboxes if the server does not support the operator. In these cases, use the search folder’s own criteria instead.
category:= Operator vs Standard Category Search
| Item | category:= Operator | Standard category: Search |
|---|---|---|
| Logic for multiple names | AND — all categories must be present | OR — any category can match |
| Syntax example | category:= “Red”, “Blue” | category:Red category:Blue |
| Works with single category | Yes, same as standard search | Yes |
| Works with punctuation in names | Requires quotation marks | Requires quotation marks |
| Supported in Outlook for Microsoft 365 | Yes | Yes |
| Supported in Outlook on the web | No | Partial |
Use the category:= operator when you need to find items that belong to a specific combination of categories, such as all client emails that are also marked as urgent. Use the standard category: search when you want a broad list of items that have any of the tags you specify.
You can now locate items tagged with multiple categories using the category:= operator in the Instant Search bar. Try combining the operator with other search properties like from: or hasattachment:yes to further refine your results. For advanced filtering, save your query as a search folder by clicking Search > Save Search.