If you want to Blacklist or Whitelist an email address, follow these steps:

Highlight the email with the address you want to Blacklist/Whitelist.
Click "More" in the SPAMfighter Toolbar and select "Blacklist" or "Whitelist".
Here you can choose if you want to Blacklist/Whitelist the email address or the whole domain.

To be sure that all emails from people in your contacts get through to you, you can import and Whitelist them. To do this, follow these steps:
Go to "More" -> "Options" -> "Filter settings" -> "Blacklists & Whitelists" -> "Whitelist email address" -> "Import".
Select your 'Address Book' and click on "Check all" -> "Add" -> "Apply"

If you get a pop-up box offering you to upgrade to SPAMfighter Pro it is because you have exceeded the limit of 5 addresses. You can fix this by buying SPAMfighter Pro here or by deleting some of the addresses in your Black/White list. If you want delete addresses, please go to: More" -> "Options" -> "Filter settings" -> "Blacklists & Whitelists