Okay so just for everyone (and for me to blow the dust off a few brain cells .. and what I understand the issue to be) .. This is a problem introduced with Exchange 2007, and affects any BES or Outlook 2003 user that is on Exchange 2007.
Essentially, a users Exchange 2007 OoO is actually stored at the top of the information for a users mailbox, and comprises of two messages in the folder. One has a message class of IPM.Microsoft.OOF.Log where the message body as a log of any OOF changes. The other is IPM.Microsoft.OOF.UserOofSettings, and this contains your Exchange 2007 OoO setting.
BTW, you cannot see these messages if you are using Outlook Cache Mode, you must connect direct to the server ;-)
All previous versions of Exchange and Outlook older than Outlook 2007 use a different mechanism for OoO. The OoO settings are stored in a users mailbox under IPM_SubTreeInbox and is a hidden associated message with a message class of: IPM.Note.Rules.OofTemplate.Microsoft.
When you use Outlook 2007 or OWA 2007, any updates to OoO are changed in IPM.Microsoft.OOF.UserOofSettings and IPM.Microsoft.OOF.Log. Then for the “legacy” purposes, Exchange 2007 writes a IPM.Note.Rules.OofTemplate.Microsoft to a users IPM_SubTreeInbox.
So you’re on Exchange 2007 and set and OoO using Blackberry, two IPM.Note.Rules.OofTemplate.Microsoft objects appear in the users mailbox. One is the original one set using Outlook and one the new OoO set using a Blackberry. For a small period of time, the new OoO may work, but after a few minutes, the Exchange 2007 Store finds these two messages and runs the “legacy” process and makes the “IPM.Microsoft.OOF.UserOofSettings” the “master” OoO.
For RIM to fix this, they will need to rewrite the OoO bit to use the new Exchange 2007 methods, that is as long are the users mailbox is on an Exchange 2007 server.
So the workaround is to set the OoO using OWA 2007 or Outlook 2007 … or as I suspect some Microsoft folk will want you to migrate to Windows Mobile & ActiveSync ;-)
It doesn’t looks like BES 4.1 SP5 fixes the issue, and we will all have to wait for BES 5.0