How can I whitelist email senders using message filters?

I understand that Thunderbird recommends managing spam by trusting senders in the Personal Address Book and/or Collected Addresses. For that to work, I would have to put the many companies who send me messages that I needn't reply to into the Personal Address Book. But I prefer to only put people I know into the Personal Address Book. So I looked for an alternative method of managing selected senders, and thought I had found one, but it's not working. The alternative I thought I'd found was to use Message Filters. I created a filter I called "Whitelist", and in the Filter Rules dialog I said to apply the filter when it is run manually, or when getting new mail, and to apply the filter after spam classification (although when this didn't work, I also tried running the filter before spam classification). I said to apply the filter when the "from" address matches a sender that I wanted to whitelist. And I said to set the spam status for such messages to "Not Spam", and to move them to my inbox. Nevertheless, emails from the sender I specified continued to be put into my spam folder. Am I doing something wrong? If filter rules cannot be used to override automatic spam handling, why does the filter UI allow you to set the spam status to "Not Spam"?