Hi, We are facing a big challenge here with default behaviour of Exchange. If User A sending email from User B to User C then he gets the NDR from Exchange Server that you dont have permission to send mail from User B, however still that mail is available on Sent Item. This sent mail can be used later for reference / approval etc. Our requirement here is If User A sending email from User B, it shouldn't go out from Outbox. Is there any possibility to restrict in Exchange Server 2010 SP2. If its not possible is there any way around to block 'From' field in outlook 2010 / 2003? but pls note that many are using on behalf of / send as permissions they will be affected by this settigs. Looking forward your best suggestions / advices.....Thanks in advance. Rgds, Natarajan

We cannot stop users from sending an email. once the message is submitted to store then it checks the sender has send-as permision or send on behalf permission. you can follow steps mentioned in this thread to disable from field in outlook http://social.technet.microsoft.com/Forums/en-US/officesetupdeploy/thread/686d5b14-d77e-4c9e-b8df-b04fbcd1ca4b/ Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. Hasnain Shaikh| My blogs: http://messagingserversupport.com