Hi allExchange Server 2007 SP1Outlook 2007 SP2I have a user that receives the error below when trying to re-schedule an existing meeting request that he created."You marked <meeting_room> as a resource. You cannot schedule a meeting with <meeting_room> because you do not have the appropriate permissions for that account. Either enter the name as a required or optional attendee or talk to your administratator about giving you permission to schedule <meeting_room>"I've checked and the meeting room is currectly set up as a resource. Other users are able to modify/re-schedule their own meeting requests with no issue.The only difference that I can see is that this user has his user account in a different forest. If this was the issue then I would expect him not to be able to create meeting requests in the first place.Please note that KB299590 does not apply in this instance. Any thoughts?Alexei

Hi, Please refer to this links: http://social.technet.microsoft.com/Forums/en-US/exchangesvrclients/thread/107d50a0-0f43-4ed4-a4cc-e9a0219b67b3 I am looking forward to your reply. Thanks, Richard.

Thanks for the reply Richard. I've found more information on the problem. Looking at the mailbox properties I see that it is normal mailbox (as opposed to a linked mailbox). The user logs on with their account in the other (non-Exchange) forest and can access the mailbox using SIDHistory. I guess not all operations within Exchange support SIDHistory, which is why we are seeing problems with this user?I will change the mailbox to a linked mailbox and see if this problem goes away.Alexei.

Hi, Would you please let me know how are you realize the resource mailbox with external account by linked mailbox? I’m looking forward to your reply. Thanks, Richard.

Hi RichardJust to clarify, it is the human user that has an external account. The resource mailbox has a disabled account in the same domain as the Exchange Server.Alexei

Hi AlexeiHave you any updates?I'm looking forward to your reply.Thanks,Richard.

Hi RichardYes, changing the mailbox to a linked mailbox resolves the issue. Alexei