Before you can act as a proxy for someone, that person must give you proxy rights in his or her Access List. As a mailbox owner, you can assign each user different rights to your calendaring and messaging information. For example, if you want to let users view specific information about your appointments when they do a busy search on your Calendar, give them Read access for appointments.
See Understanding Proxy Access for a list of functionality differences when you use proxy access.
To grant another user proxy rights to your mailbox:
Click Tools > Options.
Double-click Security, and then click the Proxy Access tab.
To add a user to the list, type the name in the Name field; when the full name appears, click Add User.
Click a user in the Access List.
Select the rights you want to give to the user.
Read: Read items you receive.
Write: Create and send items in your name, including applying your signature (if you have one defined). Assign categories to items, change the subject of items, perform tasklist options on items, and delete items.
Subscribe to my alarms: Receive the same alarms that you receive. Receiving alarms is supported only if you and the proxy are on the same post office.
Subscribe to my notifications: Receive notifications when you receive items. Receiving notifications is supported only if you and the proxy are on the same post office.
Read items marked private: Read the items you marked Private. If you do not give a proxy Private rights, all items marked Private in your Mailbox are hidden from that proxy.
Modify: You can select which options the proxy user can change. If Options is selected, the proxy user can modify any options except Security options. The Security options box is only available if Options is selected. If Security options is selected, the proxy user has access to change your password, notifications, proxy access, and send options. If given Rules rights, the proxy can edit any of your rules. If given Folders rights, the proxy user can create or modify folders.
Repeat Step 4 and Step 5 to assign rights to each user in the Access List.
You can select All User Access in the Access List and assign rights to all users in the Address Book. For example, if you want all users to have rights to read your mail, assign Read rights to All User Access.
To delete a user from the Access List, click the user, and then click Remove User.
Click OK.