Hello, If I am in Domain Admins gorup, I am able to send messages as other users. In my outlook client I change "FROM" and recipient receives e-mail shown from someone other than me. My goal is to achieve the same for few users that are not Domain Admins so their e-mails appear as from someone else (shared mailbox in this case for a special purpose). If I use "send on behalf" in Users and Computers -> Exchange General ->Delivery Options, recipient will know who's sending on whose behalf which is not what I want. Thank you.

Give them SEND AS permissions to those mailboxes instead. You can do this via ADUC/Properties of the account you want user to SEND AS/Security Then Add the user and check the SEND AS checkbox scrolling through perms Wait about an hour or 2 before it takes effect.

Hi, With the Send As permission, the recipients of a message cannot identify whether the message was sent by the actual user or another user that has been granted the Send As permission. Thanks Allen

I can't find SEND AS, can you please navigate me to it? Also, once given SEND AS permission, is it possible to change sender w/o changing this permission? They may send e-mails as themselve or someone else depending on who they deal with. Thank you.

http://www.cryer.co.uk/brian/msexchange/exch_howto_grant_send_as.htm If they need to send as other accounts, they will need SEND AS permissions for every account they want to send as.