Updated: 2009-04-09

Beginning in 2007, daylight saving time (DST) in the United States and Canada is observed for several additional weeks. This change can impact Outlook calendar items.

NoteNote:

This topic helps administrators plan how to address the DST change efficiently in their organizations. An Office Online article, Prepare Outlook calendar items for daylight saving time changes in 2007, provides detailed information for users about how the DST rules have changed and the impact on users' calendaring environments. The article also includes information about why updating users' computers is required and outlines the effect of the DST changes in different Outlook user scenarios.

To help ensure that Outlook calendars work correctly with the new DST rules, you must update Microsoft Windows and other products to reflect the new daylight saving time period. In addition, you can download and run tools that work with Microsoft Outlook and Microsoft Exchange Server to correct calendar information.

The steps you should take to update your organization's calendaring environment are listed below.

Step Action How-to instructions

1

Update Microsoft Windows on servers running Microsoft Exchange

2007 time zone update for Microsoft Windows operating systems

2

Update Microsoft Windows on users' computers

As above: 2007 time zone update for Microsoft Windows operating systems

3

Update mobile devices used to create or view calendar items

How to configure daylight saving time on Windows Mobile-based devices

4

Update Collaboration Data Objects (CDO) on servers running Microsoft Exchange

Update for daylight saving time changes for Exchange 2003 Service Pack 2

5

Use options table to determine the best method to update users' calendars

Options for updating mailboxes

6

Update users' calendars by downloading and running one or both of the Microsoft update tools:

a. Download and run the Time Zone Data Update Tool for Outlook

How to address daylight saving time by using the Outlook Time Zone Update Tool

b. Download and run the Exchange Calendar Update Tool

How to address daylight saving time by using the Exchange Calendar Update Tool

Options for updating mailboxes

You can update mailboxes by using the Time Zone Data Update Tool for Outlook or the Exchange Calendar Update Tool, or you can use both tools in combination to accomplish a complete update. The best method for your organization depends on several factors, including how many users are configured on each Exchange server and how many meetings must be updated in your calendaring environment.

For advice on which update method might be best for your organization, refer to the scenarios and options in the following table.

Option Pros Cons

Distribute the Outlook tool to each user, and then instruct users to update their own mailboxes.

This option avoids the risks and limitations of running the Exchange tool.

It is difficult to guarantee that all users will run the tool correctly and in a timely manner. Users who do not have Outlook will be unable to run the Outlook tool. An additional educational effort is needed to lessen confusion for users.

Run the Exchange tool against all affected users and servers.

This option provides a streamlined experience for users.

There are issues associated with running the Exchange tool, as described in the Exchange tool limitations table (see table later in this section).

Run the Exchange tool and update only recurring appointments. Let users update single-instance appointments in their own mailboxes by using the Outlook tool.

There is less risk involved when single-instance appointments are incorrectly updated.

The cons of running the Outlook tool are combined with the cons of running the Exchange tool.

Run neither the Exchange tool nor the Outlook tool. Ask users to examine their calendars and re-book appointments as needed.

This option avoids the issues of running the Exchange tool.

Unless all users re-book all affected appointments, some calendar items will be one hour off during the extended DST period. An additional educational effort is needed to lessen confusion for users.

Distribute the Outlook tool to each user, and then instruct users to update their own mailboxes. Then, use the Time Zone Extraction Mode of the Exchange tool to determine whether users are running the Outlook tool. If the users are not running the Outlook tool, you can run the Exchange tool.

This option reduces the risk of users not running the tool in a timely manner, and avoids the issues of running the Exchange tool.

This is not an option if users are running Office Outlook 2007.

If the Exchange Calendar Tool is an option you are considering for updating mailboxes, first evaluate the issues described in the following table.

Risk Effect Mitigation

There are many meeting updates.

Server and network performance is decreased while the Exchange tool runs.

First, determine the effect of running the Exchange tool on server and network performance by updating a small batch of users. If the load is disruptive, run the tool during off-peak hours or during dedicated maintenance hours.

The tool takes too long to run.

The Exchange tool is single-threaded. If you run the tool in Update Mode for several thousand mailboxes at the same time, the tool might takes hours or possibly days to finish.

To speed up the process, divide users into batches, then run instances of the Exchange tool on separate computers to perform the updates.

Download this book

This topic is included in the following downloadable book for easier reading and printing:

See the full list of available books at Office Resource Kit information

See Also