sieve filter move wrong email to Junk folder

[Richard]

> Date: Thursday, December 14, 2017 09:47:44 -0800
> From: Gao <gao at pztop.com>
>
> I use a sieve filter to move spam email to user's Junk folder:
># cat spam_to_junk.sieve
> require "fileinto";
>    if exists "X-Spam-Status" {
>            if header :contains "X-Spam-Status" "YES" {
>            fileinto "Junk";
>            stop;
>            } else {
>        }
>    }
>    if header :contains "subject" ["SPAM?"] {
>      fileinto "Junk";
>      stop;
>    }
> 
> Most time this filter works fine but occasionally it move non-spam
> in to Junk folder. Here is an example, this email is from dovecot
> mailling list and it end up in my Junk folder. Mailllog and header
> here. Would someone help me to figure out what went wrong here?
> 
> Thanks.
> 
> Gao
> 

  > X-Spam-Status: No, score=-2.9 required=5.0 
         tests=ALL_TRUSTED,BAYES_00


Because of the way you are bounding it, I suspect that the "YES" in
BAYES_00, at the end of that line, is triggering the mis-filing. 

Why not make:

   contains "X-Spam-Status" "YES"

a single string:

   contains "X-Spam-Status: YES"

that would be more precise and avoid this issue.