1.Open the Exchange System Manager tool.
2.Create a System Policy folder by right-clicking the Administrative Group container that contains the Exchange server, and selecting New and then selecting System Policy Container from the shortcut menu.
3.Right-click the System Policy container, and select New and then select Mailbox Store Policy from the shortcut menu.
4.The New Policy dialog box opens.
5.Select the property pages that should be available in the mailbox store policy. You can choose between the following:
•General
•Database
•Limits
•Full-Text Indexing
Enable the checkbox besides Limits and then click OK.

6.On the General tab, specify the name for the new mailbox store policy.
7.Click the Limits (Policy) tab.
8.Specify the desired storage limits and click OK.
9.The new mailbox store policy is now displayed in the System Policies container in the Exchange System Manager.
10.Right-click the Policy and select Add Mailbox Store from the shortcut menu.
11.The Select The Items To Place Under The Control Of This Policy dialog box opens.
12.Specify the name of the mailbox store that this mailbox store policy should be applied to.
13.If you do not know the name of the mailbox store, click the Advanced button.
14.Click Find Now to display the mailbox stores in the Administrative Group.
15.Select the mailbox stores to which this mailbox store policy should be applied.
16.Click OK.
17.All added mailbox stores should now be listed in the details pane of the Storage Limits policy container.
18.If you want to determine the effects of the mailbox store policy on a mailbox store, double-click the mailbox store and click the Policies tab.
19.To apply the mailbox store policy, right-click the policy and select Apply Now from the shortcut menu.