Create a message with restricted permission
Important To restrict permission to content in a message, you must have Microsoft Office for Mac Standard 2011.
Information Rights Management (IRM) allows authors to restrict permission for e-mail messages, documents, workbooks, and presentations on a per-person or per-group basis. In Outlook for Mac 2011, you can restrict a message from being forwarded. Depending on how IRM is used in your organization, you may be able to set other restrictions, such as not allowing recipients to Reply All to a message.
Restrict permission to a message
On the Home tab, click New, and then click E-mail Message.
On the Options tab, click the arrow next to Permissions, and then click the type of restriction that you want.
If you are accessing the licensing server for the first time, you have to sign in.
To remove restrictions on the message, on the Options tab, click the arrow next to Permissions, and then click No Restrictions.