We have run into an issue with EWS which affects our in-house applications. It also affects Outlook 2011 for Mac, which is built on top of EWS: Users whose mailboxes are moved to 2010 can no longer access calendars of users still on 2007, even though reviewer permissioning is set up correctly. One way to avoid this is to move all mailboxes at the same time. It seems this issue is by design: http://technet.microsoft.com/en-us/library/ee861107.aspx (Exchange 2007 and Exchange 2010 Application Coexistence), http://social.technet.microsoft.com/Forums/en-US/exchange2010/thread/539dc070-2ede-4d28-86a9-23e00f4a28ed, and also http://msdn.microsoft.com/en-us/library/bb856575(EXCHG.140).aspx --------------------- Suppose we're at the last step in the 2007 to 2010 upgrade process: moving mailboxes from 2007 to 2010. We have around 10,000 mailboxes, most of which under 500MB, but some are several GB. What is the performance of mailbox moves? What is the recommended best practice for moving over 10,000 mailboxes at the same time while minimizing downtime?

Performance of mailbox moves varies depending on lots of factors. I recommend that you take your own measurements when you move mailboxes. Be aware that the timing is not strictly by mailbox size; number of items is a variable, and there is a significant start-up and ramp-down time to be added to each mailbox as well. Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

Any update on the issue?Gulab | MCITP: Exchange 2010-2007 | Lync Server 2010 | Windows Server 2008 | Skype: Exchange.Ranger | Blog: www.ExchangeRanger.Blogspot.com

No update - I would want to know more on the best practices for moving a mailbox and how to improve performance.

Hi VP88, Thanks for your understanding an creating a new thread for the questions on moving mailboxes. To move mailbox for over 10000 mailboxes, you may consider using a csv file. For more information, please check the following link: PowerShell Script: Bulk move Mailboxes using a CSV Input File (HMC 4.0) http://blogs.technet.com/b/nzdse/archive/2011/01/14/powershell-script-bulk-move-mailboxes-using-a-csv-input-file-hmc-4-0.aspxMove Mailbox from a CSV Import file http://blogs.technet.com/b/benw/archive/2008/06/02/move-mailbox-from-a-csv-import-file.aspx Just a reminder, I would test with one user first. Regarding the error on accessing a shared calendar from Outlook 2011 for MAC, I am performing a deep research, will update you as soon as possible.

Hi VP88, Can you check the possible resolution below? 1. Configure the legacy namespace for Exchange 2007 CAS server. For more information, please refer to the articles below: Upgrade from Exchange 2007 Client Access http://technet.microsoft.com/en-us/library/dd351133.aspx 2. Based on your AD topology, configure either the ExternalURL or the InternalURL property for the Exchange 2007 CAS server. For more information, see Understanding Proxying and Redirection http://technet.microsoft.com/en-us/library/bb310763.aspx 3. Test to see if the issue continues. Note: Exchange 2010 CAS server does not proxy a client request to Exchange 2007 CAS server in the SAME AD site. Hope it is helpful. Fiona

Thanks for the quick reply. I haven't tried configuring the legacy namespace yet - I have to discuss with the system administrators, but I have doubts that this will help with Exchange Web services. Please note that I am using Outlook 2011 as an example of a Microsoft-owned application which has the exact same issues as the in-house app I am supporting. Are you completely sure that the limitation extends to all calendars that have default reviewer permissions?

Any update on the possible resolution? I got the confirmation from our internal channel that, the limitation extends to shared calendars beyond the general delegation scenario. So,for the shared calendar access issue you are encountering, you may: 1. Move the mailboxes to Exchange 2010 server using the CSV files that I suggested in my earlier poste. 2. Configure the legacy name space; thanks. Fiona