Software

It sounds like your default permissions are set to something other than 'None' for the mailboxes. Each mailbox should be owned by a particular account, and should be allowed access by nobody else. You may have used the 'Everyone' group in the administrative access.

At the server, review the properties of your Exchange server site, paying particular attention to anything which seems to be a list of users (other than the recipients list). You will probably find that you have granted global owner access to everyone somewhere.

Good luck.

This answer steered me in the right direction. I removed the nt user rights from the site container and the recipient container and the security problem seems to have cleared up. Thanks for steering me in the right direction.

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