From Microsoft:

In order to address time zone changes, this tool will help adjust calendar items in Outlook after the operating system has been updated with new time zone definitions. While this tool is being released in advance of the U.S. Daylight saving time rules change in 2007, it can be used for general adjustments of calendar items based on changes in time zone definitions saved in Windows or by the user making a permanent move to another time zone.

In Outlook for Mac, when you create a new meeting or appointment, Outlook uses the default time zone in your Outlook preferences for Calendar. If you want, you can specify a different time zone for an event as you are creating it. Install “Outlook Time Zone Data Update Tool” (you’ve installed it, I know, but please. The following table shows when users should run the Exchange Calendar Update Tool or the Time Zone Data Update Tool for Microsoft Office Outlook. Find which version your organization’s servers are running, and then determine which client programs your users are running.

Microsoft Time Zone Data Update Tool

Specifics:

--In existing recurring appointments, Outlook has encoded the current DST rules: Instances of recurring appointments that occur during the delta period will appear one hour earlier than they should.

--For existing single-instance appointments and reminders, Outlook already calculated the universal time coordinate (UTC) value upon appointment creation: If a user creates an appointment while Windows is configured for the old DST rules and the appointment itself occurs during the 'new' DST weeks, the appointment will appear one hour earlier than it should.

--Existing all-day events are associated with 24 specific hours instead of a given date: For the reasons described above, all-day events will appear to shift and thus span two days during the 'new' DST weeks.

Time Zone Data Update Tool For Microsoft Office Outlook Mac

Note: Microsoft Office Outlook 2007 can automatically detect the DST change and prompt the process that updates a persons calendar to comply with the new daylight saving time rules. However, the Time Zone Data Update Tool contains enhancements that improve what is available in Outlook 2007 and should be run instead of the out-of-the-box Outlook 2007 experience.

What do you need to know about free software?

Applies to: Exchange Server 2013

If the country or region where your organization or some of your users reside has changed their policy of recognizing Daylight Saving Time (DST), or changed the local time offset from Coordinated Universal Time (UTC), you need may need to update Microsoft Windows, Microsoft Exchange, Microsoft Outlook, or other programs to accommodate these changes.

Time Zone Data Update Tool

For more information about DST changes around the world, including links, see the Microsoft Daylight Saving Time Help and Support Center. Also visit the support Web sites of your other software suppliers to see if they require any additional updates.

Even if your time zone hasn't changed, if you interact with other computers or users globally, your computer needs to be able to perform accurate date and time calculations for events elsewhere in the world.

Installing time zone updates as soon as possible minimizes the number of meetings or appointments that are scheduled during the transition from the old time and date to the new one.

Step 1: Install the Windows DST update on all client and desktop computers

Because the Office 365 authentication system is updated when DST or a time zone changes, all Office 365 client computers need to be updated or they may experience connectivity issues.

• Make sure all client and desktop computers have installed the Windows DST update. For more information, see How to configure daylight saving time for Microsoft Windows operating systems.

Step 2: Install the Windows DST update on all servers

1. Update all your on-premises servers with the Windows DST update.

2. If you're running Office 365, update any servers that interact with the Office 365 authentication system, such as DirSync or AD FS servers. These servers must be updated to ensure uptime.

Note: If you're updating server clusters, make sure you follow the usual process for updating clusters. You update the passive server first, fail over to the passive server (which becomes active), and then update the formerly active (now passive) server. For more information about how to update server clusters and high-availability server clusters, see Update Exchange Server Clusters and High Availability Servers and How to update Windows Server failover clusters.

Step 3: Update Exchange and Outlook, where necessary, on client and desktop computers

1. If your users are using Outlook 2007 or older clients, determine which of the Exchange or Outlook time zone tools to run, using the table following this procedure.

2. Send a message to your users who need to update their computers, giving them a link to the appropriate tool.

Microsoft Outlook For Mac Update

The following table shows when users should run the Exchange Calendar Update Tool or the Time Zone Data Update Tool for Microsoft Office Outlook. Find which version your organization's servers are running, and then determine which client programs your users are running.

Outlook Time Zone Data Update Tool