As per the Amazon documentation, you should have a Send-to-Kindle email address:
When you register your Kindle DX, you'll automatically be assigned a Send-to-Kindle e-mail address. You can find this address from your Kindle's Settings screen:
- From the Home screen, select Menu. Select Settings, then use the Next Page button to scroll to the second page.
- Your Kindle device [name]@kindle.com e-mail address is listed under the Device E-mail heading.
- Learn more about modifying your Send-to-Kindle E-mail address on Manage Your Content and Devices.
Hope that helps!