Implementing tag in Microsoft Outlook 2003

Main points:
1. Outlook has category as del.icio.us or GMail has tags, by default one has to open a "Find" dialog to specified the category to find mails with selected category/categories.
2. MSN Desktop Search is able to search mails with category, e.g. "category:testing".
3. Search Folder in Outlook 2003 could be used to setup folders for categories
4. Define Views... in Outlook (version?) could be used to setup folders for categories.
5. EMail Rules can be used to assign categories automatically

I was quite fascinated by tags of del.icio.us and GMail these days, finally I tried to implement it in MS Outlook 2003 which is my company's standard email client to access exchange server. At first my focus was on implementing an Newsgator like addin which I once used. However, a term "Category" entered my view while I surfed the Internet. At second thought I realized it was actually the same as tags in del.icio.us or GMail. But to my disappointment, it is really inconvenient to find mails with categories, one has to go to "More Choices" tab page using Find dialog when MSN Desktop Search is installed, otherwise, it is much easier, you type in e.g. "category:testing" you'll have all the mails categorized as "testing" found.

My first attempt was to use Search Folders to implement virtual folders for tags as I truly enjoy this new functionality in Outlook 2003 such as "Unread mails", "For follow up". Below is what I did,
1. Pressing Ctrl+Shift+P will popup the New Search Folder dialog
2. Scroll to the bottom to select "Create a custom Search Folder", here you could also select the search source, ususally I'll take the default, but you can also select from other archived mail sources. What annoyed me most is Microsoft doesn't support searching from multiple sources.
3. Click "Choose" button to open the "Custom Search Folder" dialog.
4. Give a name for the Search Folder, such as "MyTag", then click "Criteria" button
5. Go to the second tab page "More choices", then click the "Categories" button
6. Tick on the category (or those categories) you want to search, here you can selected multiple categories, but for my case, one is always enough.
7. Click OK buttons on all the pop-uped dialogs to close all the dialogs.

That's all for Search Folders approach.

The second approach is to use custom views,
1. Go to menu View\Arrange By\Current View\Define Views...
2. Click right top button named "New..."
3. Give a name for the view
4. (steps ignored)
5. The new view will be listed on the menu item View\Arrange By\Current View\Define Views..., for my case, I turned on the Advance Toolbar so I can choose from a combobox without open so many menu hierarchy.

This approach has a shortcoming, you can only view mails from a single folder while the Search Folder one can have mails from many different folders.

The final turnout is quite promising for me, for example, I often have some mails which I need to list them in both projects, without categories, I can't place a single mail into two folders, now with categoris and Search Folders/custom views it is just another piece of cake.

Of course both these two approaches could be dramatically simplified by a program to read all the categories then to create Search Folders or custom views for every category. Hope somebody have the time.