Recently we upgraded from Exchange 2003 to Exchange 2010. The Exchange 2003 server is still up and active with a handful of users still there we are planning on migrating. Also we have mobile devices and a Blackberry BES server setup publishing to Exchange 2010 public folders free busy. The unfortunate issue is majority of our clients are still Outlook 2003.

The issue seems to be hit and miss but sometime clients cannot view other client’s calendars. They get (cannot refresh free/busy) when they add another user and check their available times. This is also true with booking resources (conference rooms) .

One thing we noticed is that the Blackberry BES seems to have created its own free/busy folders, so we have some users who use the BES on free/busy folder and other users who don’t use the BES on other free/busy folders.

If any of the clients log-in via “Exchange 2010” web-access or with a Outlook 2007 client they can view the calendaring just fine.

Thanks for your help

Nick @Toshana


3 Answers 3


After a few days of trouble shooting and support calls with Microsoft's PS. We narrowed it down to a missing SNAT pool on the F5 BIGIP that load balances the two CAS servers. The issue was strange, when a user manually updated their free\busy from a Outlook client everything would look good till the "Availability Service" updated the message. After the Availability Service touched it the message somehow became corrupt and unreadable by our old Outlook 2003 clients.


We worked on this issue with Microsoft for over a month, it turns out there was a true bug with the Free/Busy in Exchange 2010. The created a “hotfix” for the issue that resolved our issue, and I assume this hotfix is being applied to current and future service packs.


Is auto-discover working ok?
Has free-busy system folders replicated on new servers?





How do I ask a question under your question and not post an answer like GAThrawn?

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    – BenGC
    Jan 12, 2011 at 21:20

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