Is there a way to dissallow a user in an Shared mailbox to mark an email as read for example.

we would need to have a shared mailbox but want to have emails put into this mailbox in different ways
1. drag and drop from his own mailbox --> it gets marked unread when it is dropped into this shared box .... but when the mail is moved into the box it is not allowed marking as read by the user which has the shared mailbox .
2. mail was sent into this mailbox directly ... it is marked as unsread normally ... but when a user reads it which is allowed cause of shared mailbox it does not get "marked read"

When we set the userrights from the one mailbox to rxi .... then we cannot put a mail into the box :-( ....

any idea ?

thanks in advance