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:
How to create new color categories in Outlook 2007, 2010, and 2013.
You'll find some debate over which method is better for managing different types of contacts — have more than one Contacts folder (Personal, Business, etc.) or use one Contacts folder with categories. There are pluses and minuses for both. Personally, I use a combination. I have a couple of separate Contacts folders that use special
This page sums up a few things I've learned about Outlook categories and color categories, with suggestions for using and managing categories along with troubleshooting tips. Outlook has always supported categories; through Outlook 2003, they were simply Categories. Outlook 2007 introduced Color Categories by merging the short-lived colored flags with categories.