Outlook allows you to set an expiry date for emails you send, allowing your recipients to see quickly when messages are out of date. An expired message will still arrive in the recipient's inbox and can still be viewed, but will appear with a line through the sender name and subject line, as shown below.
To set an expiry date for an email message:
1. Create a new message as normal
2. Select the Options... button on the toolbar
Note: If you do not see an Options... button on the toolbar, select Tools | Options... from the menus
3. Tick the box next to Expires after: (in the Delivery options section)
4. Set the date and time at which the message expires.
5. Click Close