To whitelist or blacklist any address or domain simply log in to your barracuda account and click "Settings" and then select "Sender Policy"
On this screen you can select "Block" to blacklist or "Exempt" to whitelist a specific email address or an entire domain (Ex: Navpoint.com). Then just click "Add" to complete the changes.
If you have forgotten your password you can click here to have a reset email sent. Please note that your Barracuda and Navpoint Passwords are not necessarily the same.