rules [and no AppleScript]: Blocking spam by SpamAssassin’s X-Spam-Bar header

As I was writing my previous post about using Apple Mail’s rules and AppleScript to block spammy email messages, I realized there was a much easier way to do it, without using AppleScript. When I was going through the headers added by SpamAssassin, I noticed that the X-Spam-Bar header’s length represented the spaminess score. So instead of using AppleScript to parse the X-Spam-Score header as a number, I could just use rule conditions to weed out particularly spammy emails.

The following rule definition does almost exactly the same thing as the AppleScript in the previous post:

If [all] of the following conditions are met:
    [Subject] [Begins with] [***SPAM***]
    [X-Spam-Bar] [Begins with] [+++++++++]
Perform the following actions:
    [Delete Message]
    [Mark as Read]
    [Stop evaluating rules]

Two things might be of note here:

  • The ***SPAM*** tag in the message’s subject is added by our SpamAssassin setup automatically. We don’t actually need it to make this rule work, but I figure it probably cuts down on some processing time.
  • The X-Spam-Bar header is not initially a choice in the rule adding/editing dialog. You have to add it to the list by choosing the [Edit Header List] option from the bottom of the [Subject] select menu.

This rule takes advantage of the X-Spam-Bar header, which, if the spam score is 9.0 or greater, will contain at least 9 ‘+’ symbols, and will thus be deleted.

The one thing it doesn’t do is mark the message as spam, which helps teach Mail’s spam analysis engine. If anyone knows how to do that with Mail’s rules, please leave me a comment and let me know!

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