You can  customize the Outlook holiday file to include your own holiday information. You might choose to do this if a particular local holiday is not included in the Outlook file and you want to deploy new holiday information to a large group of people (if you just want to do this for yourself, it’s probably easier to just add events directly to your calendar).

You can open the holiday file, usually located in C:\Program Files\Microsoft Office\Office<Ver>\<LCID>\Outlook.hol, to edit which holidays are added to your calendar when you import holidays. For example, if you are using a US English version of Outlook 2007, you would usually find your holiday file at C:\Program files\Microsoft Office\Office12\1033\Outlook.hol. If you don’t know the LCID of your language, look for a folder under the Office12 folder that only has a numerical name, that’s probably the right one.

Note: You need to be a local administrator on the computer to edit the holiday file.

After you have the file open, you’ll find a listing of holidays for several different locations. Each location’s holidays start with a header, that includes the location name inside square brackets, and the number of holidays listed for that location. For example, for the United States you might see a header like this:

[United States] 168

If you add additional holidays to the file, make sure to increment the number or some holidays will be missed.

Each line inside a section represents a specific instance of a holiday. For example, the section for holidays in the United States contains a line like this:

Groundhog Day,2008/2/2

This line includes the holiday name (Groundhog Day), then a comma, and then the date the holiday occurs in the format year/month/day. To add your own holidays to the calendar, just add new lines to the bottom of the file in the same format, save the file, and then import your location’s holidays.

If you decide to edit the holiday file to add your own holidays, consider adding them as a brand new location instead of adding them to an existing location. This way you can choose to import only the new holidays without creating duplicates of the existing holidays you have previously added. For example, if you wanted to create a listing of all your associates birthdays, you could add a listing like this to the end of the file:

[Birthdays] 3
Ryan’s Birthday,2008/1/1
Ryan’s Birthday,2009/1/1
Ryan’s Birthday,2010/1/1

After you have finished editing the holidays file, remember to keep a back up. Because the file is installed with Outlook, it can be modified or replaced with the original if you install an update or upgrade to a newer version.

Outlook Command line switches: