Question : Deny a user delete access to mailbox

Hello, how would I be able to modify the access for a user to his own mailbox? I went into exchange advanced->mailbox rights, but the changes I am making don't seem to stick. Is there something else that needs to be done? I'd like him to have Read Only access and not be able to delete any mail or folders within the Inbox. Thanks!

Answer : Deny a user delete access to mailbox

From Active Directory Users and Computers (The one in Exchange) Right-click the User

1. check and Write down the mailbox alias 
2. select Exchange Tasks 
3. Select Remove Exchange Attributes (click Next as needed to complete the task) 
4. Create a Bogus user account 
5. Create a Bogus user, but do not create an Exchange account 
6. Right-click the Bogus User 
7. select Exchange Tasks 
8. Select Create Mailbox, click Next 
9. Specify the SAME ALIAS as the mailbox (click Next as needed to complete the task) 
10. Now grant your user that you want to limit access to the mailbox.