Windows Mail can download e‑mail messages to your computer, allowing you to read and reply to them offline. You might want to work offline if:
You want to reduce the amount of time you spend online, either because your Internet service provider (ISP) charges you by the hour, or because you have only one phone line and you're not using a broadband connection.
You use a mobile PC to read messages while traveling and in other situations where you can't connect to the Internet.
Open Windows Mail by clicking the Start button , clicking All Programs, and then clicking Windows Mail.
Click the Tools menu, and then click Options.
On the General tab, under If my computer is not connected at this time, click Connect only when not working offline, and then click OK.
If your e‑mail server uses IMAP, click the server name in the Folders list (located in the left pane of Windows Mail), select the check boxes for the items you want to view offline, and then click Synchronize Account.
To find out which type of e‑mail server you're using, click the Tools menu, click Accounts, select your e‑mail account in the list, and then click Properties. The account type is listed on the Advanced tab.
Click the File menu, and then click Work Offline.
Now you can read and respond to messages offline. The next time you go online and click the Send/Receive button, any messages you composed while offline will be sent, and any other actions you took while offline will be completed.