Click an appointment, meeting, email message, or contact, and then click Categorize > All Categories.

Tip You can change the name of any category. When you assign a color category, that color is used as the item's background color on the calendar grid.

Click a calendar appointment, meeting, or event.

On the Navigation Bar (Navigation Bar: Commands at the bottom of the Outlook window that enable you to quickly navigate to Mail, Calendar, People, and Tasks.), click Calendar.

At this time, you can also change the color of the category and choose a keyboard shortcut. The first time that you assign a default color category to an item, you'll be prompted to rename the category. The Color Categories dialog box is also a quick way to assign multiple categories to an item. To assign a color category from the Color Categories dialog box, you must select the check box next to the color category.

To see more categories or to create a category, click All Categories to open the Color Categories dialog box. Note Categories don't work for calendars in an IMAP account. make sure that the outlook 2016 client is up to date according to the article below. so based on my experience, i suggest you first try the steps below: 1.

You might assign all personal items to the green category and all important items to the red category i have tested in outlook 2016 and i can assign categories to emails in outlook client by right-clicking on the emails and selecting the category option. If you keep a lot of appointments and meetings on your Outlook calendar, adding color categories lets you scan and visually associate similar items.

Outlook 2016 categories