Active Directory Rights Management Services (AD RMS) is server software for Windows which is used to manage rights to documents created with with MS Office applications. Rights to MS Outlook emails, MS Word documents, and more can be restricted with AD RMS, and it can also be used to encrypt these documents.
AD RMS can protect a document forwarded to others inside an organization, and outside it. The RMS client will be pre-installed with Windows 7 and Windows 8. AD RMS is accessed by the desktop user by going to File . . . Info . . . Protect Document . . . Restrict Access.
AD RMS is available for MS Office, SharePoint, Adobe Acrobat, Internet Explorer, and other non-Microsoft software. It's good to check for it when considering new software for your firm. AD RMS can be used with Microsoft Exchange to prevent the recipient of an email from changing the content of an email, even though the email can be forwarded or replied to. The original email gets added as an attachment to the reply email.