This article was previously published under Q262399
In Microsoft Exchange, by default, only the mailbox owner has permission to access his or her mailbox. As an administrator and for troubleshooting purposes, there are times when you need to access a user's mailbox. However, when you log on to the mailbox, you receive the following error message:
Unable to open your default email folder. You do not have permission to log on.
To make yourself a delegate of a user's mailbox, open the Active Directory Users and Computers snap-in, and then follow these steps:
Right-click the organization domain name, point to View, and then click Advanced Features.
Click the Users container (or the organizational unit where the user is located).
Right-click the user account, and then select Properties.
Click the Exchange Advanced tab.
Click the Mailbox Rights button.
In the Permission window, click the Add button to add yourself to the list of those whose are allowed to access this mailbox.
In the next Permission window, click to select the Allow check box under Full Mailbox Access, and then click Apply to implement the changes.