Exchange Server and Daylight Saving Time (DST) 2007

  • Article

Important

This feature article was originally authored in February 2007 and may reference product versions that are no longer supported. For the most current information about Daylight Saving Time in relation to Microsoft products, go to Daylight Saving Time Help and Support Center.

By Scott Schnoll

This article discusses the software updates that are required for Microsoft Exchange Server and Exchange Server-related applications and platforms in order to comply with the upcoming changes to Daylight Saving Time (DST) in the United States and Canada. This article also provides information about the Exchange Calendar Update tool, which enables administrators to automate the updating of user calendars. Additional details about the updates and tools available for Microsoft Windows and affected Microsoft products, including how customers and partners can acquire the available updates, can be found at the Microsoft Daylight Saving Time Help and Support Center.

Description of the Daylight Saving Time 2007 Changes

On August 8, 2005, the U.S. Congress passed and President George W. Bush signed into law the Energy Policy Act of 2005. Among other changes, this act modifies the start and end dates for DST in the following geographic regions:

  • All of the United States except Arizona, Hawaii, Puerto Rico, the U.S. Virgin Islands, and American Samoa

  • All of Canada

    Note

    The Navajo Nation in Arizona does observe DST. The third-party Web site information in this topic is provided to help you find the technical information you need. The URLs are subject to change without notice.

When this law goes into effect on March 11, 2007, DST will start three weeks earlier and will end one week later than what has traditionally occurred. This change is typically referred to as DST 2007. Under the DST 2007 rules, in the U.S., clocks change at 02:00 A.M. local time. Following are the key dates for 2007:

  • On March 11, 2007, clocks will move forward from 01:59 A.M. to 03:00 A.M.
  • On November 4, 2007, clocks will move backward from 01:59 A.M. to 01:00 A.M.

While the change in DST applies to the U.S. and Canada, the change also affects people and organizations outside of North America. Organizations that have operations, customers, partners, or vendors based in North America will be affected. In addition, customers and systems that interact or integrate with systems based in North America, or systems that rely on date and time calculations will be affected.

Important

Mexico will not be following the new DST 2007 rules with the U.S. and Canada. Accordingly, systems configured to use U.S. time zones (for example, Pacific Time) will need to change their system configurations to use the updated Mexico time zones.

Microsoft Products Affected by DST 2007

Several products from Microsoft, including several versions of Microsoft Exchange Server, are affected by the new DST 2007 rules. Also affected are several versions of Microsoft Outlook and several versions of Microsoft Windows. Of these product lines, the three specific versions that do not need any software updates to operate correctly under the DST 2007 rules are:

  • Microsoft Exchange Server 2007
  • Microsoft Office Outlook 2007
  • Microsoft Windows Vista

Of these product lines, the products listed in Table 1 are affected by the DST 2007 rules change and require updating.

Table 1   Exchange Server, Office Outlook, and Windows products requiring updates for DST 2007

Product Details

Exchange Server 2003 SP2

An update for Exchange Server 2003 SP2 is available, as described in Microsoft Knowledge Base article 926666, Update for daylight saving time changes in 2007 for Exchange 2003. Previously, a test version of this update was released under this same article number. If you have installed the test version of this update, you should remove it before installing the final released version. The Exchange Calendar Update tool is available from the Microsoft Download Center.

Outlook 2002, Outlook 2003, and Outlook 2000

The Time Zone Data Update Tool for Microsoft Office Outlook is available from the Microsoft Download Center.

Windows XP SP2

Windows Server 2003 updates are available for production deployment for all customers through the Download Center, as described in Knowledge Base article 928388, 2007 time zone update for Microsoft Windows operating systems. While this update is being offered as optional now, after the Outlook and Exchange tools are released (enabling all updates and tools to be run at the same time), the classification of this update will likely change to either high priority or critical. At that time, if you are running the test version of the Windows time zone update released under Knowledge Base article 924840, A test version of the 2007 global time zone update for Windows is available, you should remove the test version and install the final version released under article 928388.

Windows Server 2003, Windows Server 2003 SP1, and

Windows Server 2003 R2

Windows Server 2003 updates are available for production deployment for all customers through the Download Center, as described in Knowledge Base article 928388. While this update is being offered as optional now, after the Outlook and Exchange tools are released (enabling all updates and tools to be run at the same time), the classification of this update will likely change to either high priority or critical. At that time, any customers running the test version of the Windows time zone update released under Knowledge Base article 924840 should remove the test version and install the final version released under article 928388.

Microsoft Entourage

Microsoft Office 2004 for Mac 11.3.3 Update provides updates to time zone support for Entourage, including support for DST 2007. Without this update, events during the affected periods will be off by one hour for the majority of U.S. customers.

Microsoft is providing the updates at no-cost for customers and partners on Windows platforms that are covered by Mainstream Support.

The following products are also affected by the DST 2007 rules change; however, these products are either no longer supported, or they require an Extended Support Hotfix Agreement (ESHA) or a Custom Support Agreement (CSA) to obtain the update. Customers or partners with an ESHA or CSA can request a hotfix for products in Extended Support. For more information about the current support status of your Microsoft products and the Support Lifecycle Policy, see Microsoft Support Lifecycle. Table 2 indicates which products are outside of Mainstream Support and which products require an ESHA or a CSA.

Table 2   Unsupported products and products under extended support affected by DST 2007

Product Details

Exchange Server 2003 SP1

An update is scheduled to be released in February 2007.

Exchange 2000 Conferencing Server

The update is available now for customers with an ESHA. Customers with an ESHA can request the update through their Technical Account Managers.

Exchange 2000 Server

The update is available now for customers with an ESHA. Customers with an ESHA can request the update through their Technical Account Managers.

Exchange Server 5.5

The update is available now for customers with a CSA. Customers with a CSA can request the update through their Technical Account Managers.

All Exchange versions out of Mainstream Support without an EHSA or a CSA

No workaround or update available.

Windows NT 4.0

No longer supported. All versions of Windows can be manually updated using the Time Zone Editor tool (tzedit.exe) or other techniques documented in Knowledge Base article 914387, How to configure daylight saving time for the United States in 2007 and similar articles for other countries, which is the preferred method of remediation for any product outside of Mainstream Support.

Windows 2000

The update is available now for customers with an ESHA. Customers with an ESHA can request the update through their Technical Account Managers. All versions of Windows can be manually updated using the tzedit.exe tool or other techniques documented in Knowledge Base article 914387 and similar articles for other countries, which is the preferred method of remediation for any product outside of Mainstream Support.

Windows XP SP1

No longer supported. All versions of Windows can be manually updated using the tzedit.exe tool or other techniques documented in Knowledge Base article 914387 and similar articles for other countries, which is the preferred method of remediation for any product outside of Mainstream Support.

Windows XP (no Service Pack)

No longer supported. All versions of Windows can be manually updated using the tzedit.exe tool or other techniques documented in Knowledge Base article 914387 and similar articles for other countries, which is the preferred method of remediation for any product outside of Mainstream Support.

In many organizations, Exchange Server often is used in combination with other applications and platforms, such as Microsoft Windows SharePoint Services, customer relationship management (CRM) applications, and Windows CE and other Windows Mobile devices. Some of these applications and platforms are also affected by DST 2007. Table 3 lists those Microsoft applications and platforms that often work in tandem with Exchange Server and that are also affected by DST 2007.

Table 3   Related Microsoft products affected by DST 2007

Product Details

Windows SharePoint Services 2.0

An update was released to Microsoft Update on January 9, 2007. For additional information, see Knowledge Base article 924881, Description of the update for Windows SharePoint Services: January 9, 2007.

Microsoft Dynamics CRM 3.0

An update for Microsoft Dynamics CRM 3.0 is expected in March 2007. The update will be published as Knowledge Base article 925874, Changes to daylight-saving time in 2007 for Microsoft Dynamics CRM.

Windows Mobile 2003, Windows Mobile 2003 Second Edition, and Windows Mobile 5.0

Use the updated registry information in Knowledge Base article 923953, How to configure daylight saving time for the United States and Canada in 2007 and in subsequent years on Windows Mobile-based devices to make sure that Windows Mobile-based devices display DST correctly.

Windows CE 5.0

Windows CE 4.2

Windows CE 4.1

Windows CE 4.0

Use the updated registry information in Knowledge Base article 923027, How to configure daylight saving time for the United States and Canada in 2007 and in subsequent years on Windows CE-based devices to make sure that Windows CE-based devices display DST correctly.

Note

Windows SharePoint Services 3.0 and Windows Mobile 6.0 do not require updates or changes to comply with the DST 2007 rules.

Several third-party products are available from partners and independent software vendors (ISVs) that integrate in one form or another with Exchange Server and the Exchange Server-related applications listed above. Depending on the product's level of integration with Exchange Server and the underlying technologies and dependencies of the product, these products may also be affected by the DST 2007 rule change. We recommend that you check with the vendor for each third-party application that you have integrated with Exchange Server.

Why Updates Are Necessary for DST 2007

The above applications and platforms need to have the necessary updates applied to all affected systems before March 11, 2007 to make sure that these systems use the correct time. A failure to install updates to any affected systems could result in unpredictable systems or unwanted side-effects. The known effects of not installing any updates on specific applications and platforms are described below.

Why Exchange Needs Updating

Exchange Server versions 2003, 2000, and 5.5 use a publicly documented technology called CDO (Collaboration Data Objects) to manage calendars. CDO is the public interface for MAPI. CDO uses enumerators to map time zone information. While Microsoft calendar software, such as Outlook, depends on the operating system time zone information to display time information, CDO-based applications depend on separate internal time zone tables. The DST update for Exchange Server modifies these internal time zone tables to match the changes in time zone settings. Without this update, calendar items in CDO-based applications will operate as if standard time is in effect during the extra weeks of DST. Below is a list of known CDO-based applications that are affected by the DST rules change:

  • Outlook Web Access
  • Lotus Notes Connector for Exchange 2003
  • GroupWise Connector for Exchange 2003
  • Microsoft Entourage
  • BlackBerry line of products from Research In Motion
  • Good Mobile Messaging products from Motorola Good Technology Group

An update for Exchange Server 2003 SP2 is available, as described in Knowledge Base article 926666. Previously, a test version of this update was released under this same article number. If you have installed the test version of this update, you should remove it before installing the final released version. This time zone update also includes changes for other related DST changes and time zone behavior and settings that have taken place since Exchange 2003 was originally released. It also includes changes that have previously been released as individual updates.

To operate correctly, both the client operating system update and the Exchange server update (926666) need to be installed. There are several binary files that have CDO as part of their name: CDO.dll, CDOEX.dll, EXCDO.dll, CDOSYS.dll, and CDOHTML.dll. For the DST 2007 rule changes, Outlook Web Access needs the following updated binary files:

  • Outlook Web Access in Exchange Server 5.5: CDO.dll and CDOHTML.dll
  • Outlook Web Access in Exchange 2000 and Exchange 2003: EXCDO.dll

For Exchange 2000 and Exchange 2003, Outlook Web Access does not need an updated version of CDO.dll.

Using the Exchange Calendar Update Tool

After installing the DST updates, all old recurring and single instance appointments that occur during the delta period between the DST 2007 rules and the previous DST rules will be one hour later. These appointments will need to be updated so that they will display correctly in Outlook and Outlook Web Access, and for CDO based applications. Outlook provides a tool, called the Outlook Time Zone Data Update Tool, which enables end-users to update their own calendars. The Exchange Calendar Update tool enables administrators to avoid the challenges involved with broadly deploying the Outlook tool to all users, and ensuring that each user runs the tool correctly. The Exchange Calendar Update tool is available from the Microsoft Download Center, and documented in Knowledge Base article 930879.

High-level description of the Exchange Calendar Update tool

The Exchange Calendar Update tool consists of two separate executable files, which are described in Table 4.

Table 4 Executable files included with the Exchange Calendar Update Tool

Binary Description

MSEXTMZ.exe

This file extracts time zone information from mailboxes on a server that is running Exchange Server. This file also updates mailbox calendars for a specified list of users by invoking the Outlook tool against each specified user.

MSEXTMZCFG.exe

This file is a configuration tool that walks you through most of the steps when you update a computer running Exchange Server.

Risks of running the Exchange Calendar Update tool

There are two issues to consider before you run the Exchange Calendar Update tool. Table 5 lists these issues, their potential effects on the IT infrastructure, and on users and their mitigation strategies.

Table 5 Risks of running the Exchange Calendar Update Tool

Risk Effect Mitigation

There are lots of meeting updates.

Server and network performance is decreased.

Determine what the effect on the server and network performance may be by updating a small batch of users first. If the load is disruptive, run the tool during off-peak hours or during dedicated maintenance hours.

The tool takes too long to run.

MSXTMZ.exe is single threaded. If you run this file in Update Mode against several thousand users at the same time, the Exchange Calendar Update tool may take many hours or possibly days to finish.

To speed up the update process for all mailboxes, divide the users into batches, and then run instances of MSXTMZ.exe on separate computers to perform the updates.

Options for updating mailboxes

Table 6 lists five options that can be used to update user mailboxes to use the DST 2007 time zone rules.

Table 6 Options for Updating Mailboxes

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 Calendar Update 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 Calendar Update tool against all affected users and servers.

This option provides a streamlined experience for users.

There are issues associated with running the Exchange Calendar Update tool, as described in the previous table.

Run the Exchange Calendar Update 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 Outlook tool are combined with the cons of running the Exchange Calendar Update tool.

Run neither the Exchange Calendar Update 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 Calendar Update 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 Calendar Update tool to determine whether users are running the Outlook tool. If the users are not running the Outlook tool, the administrator can run the Exchange Calendar Update tool.

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

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

Recommendations for Running the Exchange Calendar Update Tool

The Exchange Calendar Update tool is single-threaded, and running the tool in Update Mode against several thousand users at one time may take many hours and possibly even days. When running the Exchange Calendar Update tool, we recommend that you:

  • Perform the updates on a small number of mailboxes first to gauge load on the servers and network. This will help to avoid minimize the effects that running the tool will have on system performance and end-user experience. To speed up the process of updating all mailboxes, you can divide the users into groups and update those groups using separate computers.
  • Verify that the correct time zone is set for each mailbox. If the wrong time zone is set for a mailbox, then the appointments on the calendar in that mailbox will be moved incorrectly. To minimize the chances of setting the wrong time zone, you can group user mailboxes based on time zones and run the Exchange Calendar Update tool separately for each time zone.

Misuse of the Exchange Calendar Update tool can negatively affect your IT environment and your end users. We recommend that you consider all options and carefully analyze the impact to your environment and end-users before running the Exchange Calendar Update tool.

Why Outlook Needs Updating

To display the correct time for meetings scheduled during the DST period, end users need to have their operating systems updated to reflect the new time zone definitions. Users will then either manually change the Calendar time zone (available from the Calendar Options dialog on Tools | Options) or respond to the automatic prompts to change their Calendar time zone that will occur 1 to 7 days after the DST rules are updated on the computer.

Without all the necessary updates, the following issues will occur for Outlook calendar items that are active during the weeks of March 11, 2007 to April 1, 2007, and October 28, 2007 to November 4, 2007:

  • Appointments and reminders will appear one hour earlier than they should be.
  • All-day events will shift and span two days because these events are associated with 24 specific hours rather than an individual date.

Microsoft has incorporated a new feature into Office Outlook 2007 to help adjust calendar items affected by time zone changes. For other releases of Outlook, Microsoft has released an Outlook Time Zone Data Update tool to the Download Center. For details about the Outlook Time Zone Data Update tool, see Knowledge Base article 931667, Addressing Daylight Saving Time using the Outlook Time Zone Data Update Tool.

Using the Outlook Data Update Tool

The Outlook Time Zone Data Update tool is necessary to update calendar items that occur during the DST periods described above for versions of Microsoft Outlook earlier than Outlook 2007. Table 7 describes when you should download and run the Outlook update tool.

Table 7   When to run the Outlook Data Update tool

Outlook 2007 Outlook 2003, Outlook 2002, Outlook 2000

Not required to use the Outlook update tool. However, it is highly recommended because the tool includes numerous improvements.

You should run the Outlook update tool.

In environments running Microsoft Exchange, the Exchange Calendar Update tool can be used to update multiple mailboxes simultaneously.

In environments running Microsoft Exchange, the Exchange Calendar Update tool can be used to update multiple mailboxes simultaneously.

Why Directory Servers Need Updating

Many applications get their date and time information from the operating system. In addition, directory servers running Windows 2000 Server or Windows Server 2003 need to have their time synchronized for Kerberos authentication to work correctly. Kerberos works by exchanging time-stamped authenticator identification tokens. By default, directory servers have a maximum tolerance for computer clock synchronization of 5 minutes. This is known as clock skew. Clock skew is the range of time allowed for a server to accept Kerberos tickets from a client. If the clock skew is greater than 5 minutes, Kerberos authentication fails, which results in cascading authentication failures for Windows Server, Active Directory, Exchange Server, and end users.

Process for Updating Affected Systems

When you apply the DST updates throughout your organization, we recommend deploying the patches in a specific order. This approach minimizes the chances of error, and it will ensure that dependency systems are updated first. The specific order of deployment for the updates is:

  1. All directory servers, including directory servers running Exchange Server
  2. All member servers, including member servers running Exchange Server
  3. All workstations, mobile devices, and other clients

Apply the updates for these systems in the following order:

  1. Server operating system updates
  2. Exchange Server application updates
  3. Client operating system updates
  4. Any third-party server-based application updates
  5. Outlook application updates
  6. Any third-party client-based application updates

When you apply the DST updates, you do not need to reboot any systems. After the updates have been installed, you can use the Exchange Calendar Update tool or the Outlook Data Update tool to correct the time zone settings for all existing calendar items.

Post-Update Recommendations

After your systems have been updated, we recommend that you give extra attention to appointments scheduled during the extended DST period. You should consider appointments that occur during the DST period as suspect until all meeting invitees (both internal and external) have indicated that the item shows up correctly on their calendar. To minimize confusion during the affected date ranges, you can:

  • Include the time of the meeting in the e-mail request so that invitees can double check the correct meeting time (such as, "Project Meeting - 11:00 A.M. Eastern Time").
  • Accept prompts to update time zone information when requested.

Ultimately, only end users will know if their calendars are correct or not. We recommend that you notify all of your end users, make them aware of this issue, and advise them to consider any affected appointments to be suspect. If necessary, end users can verify the times themselves and with any other invitees. Using methods such as writing out the meeting time in the body of the meeting request can also be beneficial.

Frequently Asked Questions

Below is a list of frequently asked questions about the DST 2007 rule changes as they relate to Exchange Server.

Q: What versions of Exchange Server require updates?

A: Exchange Server 2003, Exchange 2000 Server (including Exchange 2000 Server Conferencing Server), and Exchange Server 5.5.

Q: What versions of Outlook require updates?

A: Outlook 2003, Outlook 2002, and Outlook 2000.

Q. Why does Exchange Server require an update?

A. Exchange Server 2003, Exchange 2000 Server, and Exchange Server 5.5 use a publicly documented technology called CDO (Collaborative Data Objects) to manage calendars. CDO uses enumerators to map its time zone information so that it does not need to query the operating system each time it needs time zone information. Outlook is also a consumer of this technology, as is Outlook Web Access, the Lotus Notes Connector, and the GroupWise connector. CDO is also used by many third-party applications.

Q: Knowledge Base article 926666 states that "Collaboration Data Objects (CDO)-based programs such as Outlook Web Access depend on separate internal time zone tables. This update modifies these internal time zone tables to match the DST 2007 changes in the time zone settings." Does a CDO-based calendar item always use these separate internal time zone tables?

A: It depends on the behavior of the application. Time zone tables are stamped on recurring calendar items during creation, and they may be updated if the recurrence is changed. If a CDO-based application created the calendar item, the time zone rules stamped on the item will match the CDO time zone tables. If Outlook creates the calendar item, the time zone rules stamped on the item will match the operating system time zone rules.

Q: If I create an appointment in Outlook Web Access, but always reference and view it in Outlook 2003 or Outlook 2007, will it now use my operating system time zone rules in Outlook, or will it use the CDO-based time zone rules?

A: All applications interpret calendar items using the time zone rules stamped on the item. Because the item was created by Outlook Web Access, all subsequent viewings by any application interpret the calendar item based on the time zones stamped on the item by Outlook Web Access (assuming the recurrence isn’t updated by another application at a later point in time).

Q: Will Outlook users have correct time zone settings for their calendars if their Exchange server is not updated?

A: Outlook does not require updates on the Exchange server; it only requires the client operating system update. Visit Prepare Outlook calendar items for daylight saving time changes in 2007 for more information about updating Outlook.

Q: Will Outlook Web Access users have correct time zone settings for their calendars if their Exchange server is not updated?

A: No, items will be one hour off during the affected time periods (March 11-April 1 and October 28-November 4). Furthermore, in a mixed environment some of your calendar items would be off and some wouldn’t. This situation would be very confusing for end users, and it would negatively affect productivity. Each item would have to be independently verified, which is impractical in most organizations.

Q: Instead of applying updates to the systems, will changing the time zone temporarily for the one-hour difference using group policy or some other means correct problems with calendar time zone settings?

A: This approach might work for some situations, but it won't work for all situations. Each item would have to have to be independently verified, which is impractical in most organizations.

Q. What does the Outlook Data Update tool do?

A: There are two aspects to DST rule change: one with the CDO platform and one with the actual data stored by Outlook. CDO always uses its own internal table of time zone definitions. The CDO hotfix updates the CDO binaries with the new time zone information. The issue with the actual data in appointments relates to the fact that single-instance appointments are at the time based on wrong Coordinated Universal Time (UTC), and recurring appointments have the wrong time zone data. In both cases, the time zone information is determined by the application that created the appointment and the time zone rules in use by that application at the time the appointment was created. The Outlook Data Update tool is intended to update data in the Outlook store to correctly reflect the new time zone rules. The Outlook Data Update tool cannot be run without user intervention. It must be downloaded from the Microsoft Download Center and run through explicit user interaction or a script that launches it under the user’s security context.

Q: What is the Exchange Server Calendar Update tool?

A: This is a server-side form of the Outlook Data Update tool that is intended for administrators. This tool automatically updates client mailboxes without any user interaction. The Exchange Server tool allows you to apply the time zone update in silent mode to a set of specific mailboxes on the Exchange server. Because the update is silent, the end user will not have a chance to uncheck appointments that do not need updating. As might be expected, the Exchange tool only works on server-side calendars. All local calendars must be updated by using the Outlook tool.

Q: How is the target time zone reflected in Outlook items?

A: Single-instance appointments are stored in UTC. The UTC time at which they are stored is determined by the computer used to create the appointments. Outlook 2007 can display this time zone information. In versions of Outlook prior to Outlook 2007, there is no indication of the time zone in which an appointment was created. Recurring appointments have the full time zone definition embedded in their data. In other words, the appointment itself understands exactly what the time zone definition and DST transition dates for it should be.

Q: Why are the tools called "Time Zone Data Update tool" rather than referring to the DST 2007 update specifically?

A: The tools have a generic name because they can move appointments between any two time zones. In the case of the DST 2007 change (or any other modification to time zone rules), the tool is moving appointments from the old versions of the modified time zones to the new versions. If the tool notices that there are new rules for a given time zone, it can automatically try to transition any appointments that are affected by the change into the updated time zone. There are two cases:

  • Recurring appointments   In this case, the appointment item has the time zone definition embedded in it, so the tool compares that time zone definition to the updated time zone definition. If they do not match, the tool rewrites the appointment with the updated time zone information.
  • Singe-instance appointments   Items created using versions of Outlook prior to Outlook 2007 do not contain time zone information; therefore, the tool cannot determine whether or not these items need updating. The tool currently assumes that any single-instance appointments in the affected time period were generated using the old time zone rules and offers to update them. If the user has created single-instance appointments in the changed period of time after applying the operating system hotfix that updates the time zone definitions, but before running the tool, then they will need to be careful to tell the tool not to update them (the tool offers to show them a list of all appointments that are thought to need updating and allows the user to uncheck any of those appointments to keep them in place). Because single-instance appointments do not contain any time zone information, those single-instance appointments that were targeted at an unaffected time zone but happen to fall within the affected dates of the time zone that has been modified will also be identified by the tool as requiring update.

Q: Do the time zone updates affect deferred delivery of messages if some or all of the updates are not applied?

A: Deferred delivery is based on local time, so it is unaffected.

Q: Are Task items affected by the time zone updates?

A: Task items use a time and not a date as the reminder. When the Data Update tool is used to update a calendar, it also processes the reminders folders and updates any items that need updating.

Q: When should I run the Data Update tools?

A: The Data Update tools can be run manually at the discretion of the end user or administrator after the operating system time zone updates have been installed. It is preferable to run the Data Update tools as close to the time as possible at which the operating system time zone updates are applied to all computers because that minimizes the likelihood of having single-instance appointments created after the operating system time zone update was applied but before the Data Update tool was run.

Q: If I only run Outlook 2007, do I still need to run the Data Update tool after applying the operating system updates?

A: Because Outlook 2007 has the updated time zone rules already embedded in it, you are not required to manually run the tool (nor use the Change Calendar Time Zone feature of Outlook 2007). After the operating system updates are installed, Outlook 2007 automatically detects that the operating system's time zone definition has changed, and it automatically prompts the user to update the affected items. To minimize the impact to the end user, the update process in Outlook 2007 runs at a random time between 1 and 7 days after the system’s time zone definition changes (not the time at which the changes takes effect). On Windows Vista, this change occurred on January 1, 2007, which was when Windows Vista clients automatically transitioned to the DST 2007 rules. On other Windows operating systems, this change will occur after the operating system updates have been applied.

Q: Why doesn’t the Data Update tool update all of my affected appointments?

A: The tool only updates appointments for which the user is the organizer and then automatically sends updates for those appointments to all other attendees. A calendar will not be 100 percent accurate until the calendar’s owner has run the Data Update tool and all other users that organized meetings to which the calendar’s owner was invited have also run the tool. This is another fundamental reason why you should treat all potentially affected appointments as suspect and verify the times themselves and with any other invitees.

Q: What happens if I run the Data Update tool multiple times?

A: The tool correctly stamps the appointments it updates with the time zone information in which they were encoded. Therefore, it is generally safe to run the tool multiple times because it will see all of the appointments that were updated and ignore them. Note that if the user explicitly asks the tool to ignore a set of appointments (for example, single-instance appointments that are targeted at a different time zone or that the user created after updating time zone rules but before running the time zone update tool), the tool will continue to discover those appointments in future runs and the user will have to explicitly ignore those appointments on each run.

Q: What happens if my end users use multiple computers, and some of those computers do not have the updates applied?

A: After the Data Update tool has been run from a computer that has the DST updates applied, be careful about using computers without the updates because appointments will be created with out-of-date time zone information and you will have to run the tool again to update them.

Q: Will there ever be an automated way of running the Outlook Data Update tool?

A: In addition to the Exchange version of the tool that can be run by the administrator on behalf of users, you can configure the tool to run silently on user computers using login scripts using regular mode (where the user is prompted) or using quiet mode (where the calendar is updated without user intervention).

Q: Are there plans to make the tool deployable via Windows Server Update Services (WSUS)?

A: No. The tool cannot be deployed or launched through WSUS because it requires that it be run under the user's security context.

Q: Microsoft Office XP, which includes Outlook 2002, entered into its Extended Support Phase on July 12, 2006. Will the update tool work for Outlook 2002?

A: The Outlook Data Update tool is independent of the version of Office. It is being tested with and will operate on Outlook 2003, Outlook 2002, and Outlook 2000.

For More Information

For more information about the effects of the DST rule changes on products from Microsoft, as well as other time zone-related information, see the following Knowledge Base articles and Web sites.

General Information

Microsoft Windows

Microsoft Exchange Server

Microsoft Office and Microsoft Office Outlook

Other Microsoft Applications

Non-U.S. Time Zones

Non-Microsoft Products

For DST 2007 information about some of the third-party products that are often used with Exchange Server, see the following third-party Web sites:

Note

The third-party Web site information in this topic is provided to help you find the technical information you need. The URLs are subject to change without notice.

Additional Information

For additional information about DST and DST 2007, see the following third-party Web sites:

Note

The third-party Web site information in this topic is provided to help you find the technical information you need. The URLs are subject to change without notice.

Scott Schnoll - Senior Technical Writer, Microsoft Exchange Server