Info on the hotfix package for the Outlook tool for daylight saving time

I’m posting some information courtesy of our Outlook team as we just released the hotfix package for the Outlook Time Zone Data Update Tool. For more details please refer to


Steps to reporting the changes that will be made by the Outlook Time Zone Data Update tool.

You can see what modifications will be made by the Outlook Time Zone Data Update tool by using the /REPORTINGMODE option. This option creates a log that can be used for planning purposes. /REPORTINGMODE does not perform any modifications, and instead it logs the items that would be modified if the tool were not run in Reporting Mode to the Application event log.


Steps to prevent rebasing of SINGLE instance items created after the date on which the operating system time zone updates were applied.



Steps to rebasing calendar items and suppressing calendar updates.

tzmove.exe  /FORCEREBASESUPPRESSALLUPDATES (referred to as SuppressAll in this document)

This option is used to rebase all single instance items (if no time zone property exists), and any recurring items that were creating using the 2006 DST rules, regardless of the organizer.


This mode will not send any updates for any reason.   When the organizer’s calendar is rebased, the meeting is shifted by 1 hour.  If the rebasing is performed using either the SuppressAll or SuppressExchange command-line parameters, then no updates will be sent to the recipient in the non-observing time zones. As a result, those attendees’ calendars will be an hour off and they will be an hour late for the meeting.


Steps for rebasing resource mailboxes using the auto accept agent (AAA)

Make sure AAA is up and running on server


Patch the Client OS


Run the /FORCEREBASESUPPRESSALLUPDATES mode outlook dst tool ( tzmove) against all resource mailboxes with AAA enabled from a  client.


It’s important to make sure AAA is running during this process – this is the key for the end users to get the acceptance mail for the updated meetings they organized.

Run the tzmove in normal mode against all the other mailboxes, including the ones organized meeting with the resource mailboxes


Steps for DirectBooking

For DirectBooking Run the tzmove with / FORCEREBASESUPPRESSALLUPDATES against resource mailboxes. – at this step, the meetings are moved to the right time slots.


Run the tzmove in normal mode against all other mailboxes. – meetings might become tentative on the resource mailbox if someone use outlook logon to the resource mailbox after the rebase.


Steps for rebasing calendars items stored in public folders.

tzmove.exe -QUIET \\Public Folders\All Public Folders\Folder1\Sub Folder\Calendar


tzmove.exe -Q –ONLYRECURRING \\Public Folders\All Public Folders\ProjectZ\Meetings\\Notes\Calendar


In the second example above, a public folder called Meetings\Notes contains the public folder calendar. Because this public folder name includes a backslash (\), the path representing the folder contains a double backslash (\\).


You can also rebase calendar items stored in additional calendars that may exist in a user’s mailbox. An example command for rebasing those items is:


tzmove.exe -Q \\Mailbox – User\Second Calendar


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