Using Background Colors to Show Spam Levels
SpamSieve sets the colors of spam messages to reflect how spammy it thinks they are. The order, from most to least spammy, is: Blue, Gray, Purple, Red, Orange, or Yellow. Good messages are left uncolored. Thus, if you are skimming the Junk mailbox for false positives, pay the most attention to the yellow and orange messages. The SpamSieve - Change Settings command lets you enable or disable spam message coloring.
Spam messages caught by a server junk filter are not processed by SpamSieve and, thus, not colored. (See also: Separating Spam Caught by SpamSieve and Server Filters.)
Using a [Score] Rule to Filter Spam Messages By Color
The Setting Up Apple Mail section of the manual shows how to create a single rule in Mail that puts all the spam messages in a single Junk mailbox. You can also use multiple rules in Mail to file messages into different mailboxes (or otherwise process them differently) based on how spammy they are. The normal SpamSieve rule looks like this:
To separate spam messages by color (spamminess), you should instead create two or more rules. The first rule should be named SpamSieve [Score]. As above, you probably want the conditions to be Every Message. When this rule is applied, SpamSieve will calculate the spam score of the message and set its color accordingly. The actions of the [Score] rule will be ignored.
Below the [Score] rule, you can create one or more rules that process messages based on their color:
Example 1: Blocklisted Messages in Trash
To move blocklisted messages to the trash and other spam messages to the Spam mailbox, you would need three rules:
SpamSieve [Score] (calculates the spam score/color) / Every Message / Move Message to mailbox All Junk
SpamSieve [Blue] (move very spammy messages to the trash) / Every Message / Move Message to mailbox All Trash
SpamSieve [Spam] (move the remaining spam messages) / Every Message / Move Message to mailbox All Junk
Example 2: Per-Color Spam Mailboxes
To put each color of spam in a separate mailbox, you would need seven rules:
The unnumbered Spam mailbox will hold the messages that you manually train as spam. If desired, you can drag the other mailboxes inside the Spam mailbox.
Example 3: Sorting Messages By Spamminess
You can sort the messages by spamminess. Apple Mail in macOS 10.7 and later cannot sort messages by color, but it can sort them by flags. Thus, you can set up rules like this:
and then choose View ‣ Sort By ‣ Flags. (The flag colors are chosen so that the messages will sort in order of spamminess; this is why they do not match the message colors.) When using this rule, you should set the AppleMailTrainGoodClearFlags option in the Esoteric Preferences to have SpamSieve clear the flags when training a message as good.
Currently, there is a bug (Radar 21468415) in macOS 10.11 where the feature to sort by flags does not work.