Here is the scenario, all o f a sudden you discover everyone can see everyone's mailbox on your SMTP domain. Full explicit permissions on the object (everyone), including Receive As permissions seems to assign everyone. Everyone" group has been granted "Send As" and "Receive As" rights I have seen this, may occur after migration scenarios.
To see the Security Tab on ESM, (Exchange system manager) copy the code below and paste into a notepad and save it as "ShowSecurityPage.reg" on your desktop. Go ahead double click on it to make the register changes.
- Copy and paste the code into notepad
- Click file Save
- Name the file ShowSecurityPage.reg
- Click on save as type, change it to all files
- Save it on your desktop, and double click on it to make the changes
Windows Registry Editor Version 5.00