Change Category when Task is marked Completed
Use the ItemChange event to run a macro when the value in a field is changed in Outlook. In this example, when a task is marked complete, the Category is updated.

Print a list of Outlook Categories and their Colors
How to use VBA to create a list of your Outlook categories and their assigned colors. For Microsoft Outlook 2007 and up.
Understanding Outlook and Live Mail "Categories"
I've had a few questions about categories in Office Live Mail accounts not syncing to Outlook using the Outlook connector. This isn't a problem with Outlook or the connector but rather with the use of the term "Category" in Hotmail/Live accounts. Hotmail lets you assign contacts to categories; Outlook lets you assign categories to contacts.

Conditional Formatting by Contact Category
How to apply rules or automatic formatting to messages and meetings with people in specific categories.

How to Upgrade to Color Categories
After upgrading to Outlook 2013, 2010, or 2007, users need to convert categories to color categories to add their categories to the master category list.

To Add Color Coding to Calendar items
Many people want to be able to color-code their Outlook calendars to distinguish between business and personal appointments, for example. Having been on the wish list for years, this feature finally arrives in Outlook 2002 in the form of Labels and Outlook 2007 adds colors to categories. See Understanding Outlook's Calendar patchwork colors for display

To set up Outlook Subcategories
You can supplement Microsoft Outlook's built-in Categories field with your own Subcategory field, or use a category naming convention to allow you to better organize and group "subcategories" together. Method #1 | Method #2 | Method #3 | More Information Method 1 – Custom Keyword field Add a new Subcategory field to a folder like

Outlook Categories, Flags, and IMAP Accounts
Categories and flags are not available in all of my folders in Microsoft Outlook. I can use categories and flags on mail in my POP3 account but categories are not available in my IMAP account and flags are limited to one flag, no reminder. Why? The IMAP protocol doesn't support the Category and Flag properties
Printing Calendars with Color Categories
Some Outlook 2007 users are having problems printing calendars with the events colored with color categories. In most cases, the problem printer is an HP and its correctly configured to print in color. HP support documents have this to say about the problem: Some or all of my jobs print in monochrome (black) only. How
Sending Categories on Email Messages
To avoid releasing potentially private information on outgoing email messages, categories are not sent with email in Outlook 2003 and up. When you use categories with internal codes or potentially embarrassing keywords, the recipient will not see them. If you need to send categories on outgoing email you can use the SendPersonalCategories registry entry. Warning:

