I just installed Exchange 2013 CU1 in Server 2012. I created users and mailboxes. One user need to have full access and send as right to another mailbox. I delegated it via Exchange Admin Centre.
Then I configured outlook 2010 on one of the computer. The mailbox over which the user has full access permission showed up on outlook but when I expand it, I get following message:

"Cannot expand the folder. The set of folders cannot be opened. The attempt to log on to Microsoft Exchange has failed."

Is there a way we can fix this issue?

Have you checked for any replication issue?

There are no other Exchange servers to replicate to. It is a fresh install in a new company.

If the user has got a Linked mailbox, you need to give permission to corresponding 'LinedMasterAccount'. Have you considered this too?

How do you do that? All the delegations been done from Exchange Admin Centre. 

Run the cmdlet:

get-mailbox 'user' | fl LinkedMasterAccount

The permission should be assigned to the account name shown as the result

Hi,

To expend the second mailbox in Outlook, you need to grant sufficient permission on each sub-folders.

Please take a try and let me know the result.

I have experienced the same issue. We installed Exchange 2013 and Outlook 2010 users cannot expand the additional mailbox.

To allow access to the additional mailbox we modified the permissions using the ECP website and assigned Full Access Rights. So for example User 1 has full Access Rights to User 2.

No what is interesting is that Outlook 2013 users seem to be able to access the shared mailbox.

It was my understanding that once Full Access Rights had been assigned that was sufficient to access the additional mailbox.

It has been mentioned here that the additional mailbox should have sufficient permission on each sub folder. This goes against the principle of Full Access Rights to the mailbox.

Please advise.