Microsoft Outlook 2003 ships with a very handy feature that lets you recall an email that you've already sent. This is very useful, if for example, you've forgotten to attach a document to a message that you have already sent or maybe mistakenly typed the wrong time for an important meeting. Here's how you recall an email:

- Click Sent Items. Select and email and open it.

- Once the message has opened, click Actions -> Recall this message

To recall the email:
- Select Delete unread copies of this message(The recipient needs to have Outlook opened for this to work)

To replace the email:
- Select Delete unread copies and replace with a new message, click OK. Now type your new message.

- Tick Tell me if recall succeeds or fails for each recipient. Click OK