How to highlight all holidays in an Outlook calendar?

To highlight all imported holidays in bulk in an Outlook calendar, please do as follows:

1. In the "Calendar" view, select any one of imported holidays to activate the "Calendar Tools", and then click "Appointment" > "Categorize" > "All Categories". See screenshot:

2. In the opening Color Categories dialog box, please click the "Holiday (not in Master Category List)" in the category list box, and then click the "New" button. See screenshot:

3. In the opening Add New Category dialog box, (1) "Holiday" is entered in the "Name" box by default, please do not change it; (2) Specify a color for this new category from the "Color" drop down list; and (3) click the "OK" button. See screenshot:

4. Click the "OK" button in the "Color Categories" dialog box.

And now all holidays are highlighted by the specified category color at once. See screenshot:

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