Hi

I am facing a problem with a requirement as below. please help me out

The Reply to All feature of Outlook has been identified as a significant risk for the organisation.  Through careless use of Reply to All E-mail correspondence is occasionally sent to inappropriate recipients, and on occasion this can have serious implications for the organisation.  For example client confidential information being sent to a third party or inappropriate comments damaging the firm’s reputation.
To reduce the likelihood of this happening in future, the Reply to All function in Outlook has been modified so that whenever the recipients of a reply contains an external E-mail address or a distribution list that might contain an external E-mail address, the users are prompted to confirm that they really do wish to send to those users/distribution lists