Outlook categories are colored labels you can attach to messages without moving them into folders. A single email can have multiple categories, making them useful for scanning, sorting, and searching.
Does this affect you?
Use this for classic Outlook for Windows, new Outlook, and Outlook.com when you want labels such as Urgent, Follow Up, Finance, Waiting, or Client without changing where the email lives. Category behavior varies slightly by app version.
Apply a category to an email
Start with one message.
- Right-click the message in the inbox or message list.
- Hover over Categorize.
- Choose a color category, such as Red Category or Blue Category.
- Look for the colored square beside the message.
- To remove it, return to Categorize and click the same category again or choose Clear All Categories.
Rename and recolor categories
Names make colors useful.
- Right-click a message, hover over Categorize, and choose All Categories.
- Select a default category such as Red Category.
- Click Rename and enter a meaningful name.
- Use the Color dropdown to change the color if needed.
- Click New to create another category.
- Click OK to save.
Auto-apply a category with a rule
Rules can tag incoming mail for you.
- Right-click a message that matches the sender or subject pattern you want.
- Choose Rules > Create Rule, or use Manage Rules & Alerts > New Rule for more conditions.
- Set the condition, such as from a person or subject contains words.
- Choose assign it to the category category.
- Click the underlined category link and choose the category.
- Save the rule and decide whether to run it on existing messages.
More control
Search by category
Click the search box and type category:Urgent, replacing Urgent with your category name. Outlook can find tagged messages across the searched folders.
Categories sync by account
For many Microsoft accounts, categories follow the mailbox across desktop, web, and mobile after sync. If they do not appear, confirm both apps are using the same mailbox and give syncing time.
Use Quick Click
Right-click a message and choose Categorize > Set Quick Click to choose a default category. Then one click in the category column applies it.
Categories are not flags
A flag creates follow-up behavior and can appear in To Do. A category is a label. Many people use both: category for type, flag for action.
Sources
- Microsoft Support – Categorize items by color in Outlook (2025)
- Microsoft Support – Assign a color category to an email message (2025)
- Microsoft Support – Manage email messages by using rules (2025)