Thunderbird's filtering features almost solve a massive problem, and that is false positives from spam filters such as Spampal. Using Thunderbird's filtering rules, it's possible to filter mail from anyone in the Personal Address Book, separately from other mail. This provides at least two ways to "almost fix" false positives.
Note, the techniques on this page do not discuss or use Thunderbird's internal spam filter at all - indeed, if using Spampal, Thunderbird's internal spam filter should be disabled. The techniques on this page assume Thunderbird's internal spam filter is disabled, like this:
Note, below, the term "trusted sender" refers to anyone in the Personal Address Book. The term "untrusted sender" refers to anyone who is NOT in the Personal Address Book. Personal Address Book (PAB) refers to the feature in Thunderbird of the same name. The term "spam folder" refers to a folder created to hold spam (this is independent of, and not related to, Thunderbird's internal "junk" folder). The term "false positives" refers to mail which has been marked as spam by Spampal, when in fact it is not spam.
This will mean that mail marked as **SPAM**, if sent by someone in the PAB, will be left in the inbox. It means that mail from trusted senders will NOT end up in the spam folder, even if it is marked as **SPAM** by Spampal.
Method: create a single filter with TWO rules:
Create the rules as follows:
Click the plus button to add a second rule. Note the isn't in the rule (this is the opposite setting to the method used in technique 2 below). In the action panel, tell the filter to move the mail to the spam folder. Ensure that the PAB rule is the SECOND rule. Ensure "match all of the following" is selected. The effect of the PAB rule is to negate the detection of the **SPAM** marker, if the mail is from someone in the PAB - in essence, disabling the **SPAM** detection for trusted senders only.
This will mean that mail from untrusted senders will be left in the inbox. If this rule is placed before the rule that tests for Spampal's **SPAM** marker in the subject line, it means that mail from trusted senders will NOT end up in the spam folder, even if it is marked as **SPAM** by Spampal. Mail from trusted senders will always end up in the "trusted" folder - never the inbox, and never the spam folder. The inbox will end up containing "mystery" mail that is not marked as spam, but is not from anyone in the PAB.
Method: create TWO filters with a single rule each:
Ensure the "trusted senders" filter runs BEFORE the test for Spampal's **SPAM** marker. This is done by placing the filter above the **SPAM** filter, in Thunderbird's list of filters (click the "Move Up" button to do this).
Create the rules as follows:
Note that neither of the techniques above are a perfect solution - legitimate mail from untrusted senders may still end up in the spam folder. The sender must be in the PAB for either of the above techniques to work.