[exim] HowTo integrate Spamassassin working?

Hello experts,

i setup a virtual mail system with exim and it is working so far.
But i could not solve the problem to alter the Subject if a mail is Spam.

Here is my configuration:
_____________________________________________________________

spamd_address = /run/spamd.sock

begin acl

acl_check_data:

  deny  message = This message is classified as UBE (SPAM) and therefore rejected. You scored $spam_score points.
Congratulations!
       condition = ${if >{$spam_score_int}{${eval:200}}{true}{false}}

       warn  spam = nobody:true
       condition = ${if >{$spam_score_int}{50}{1}{0}}
       remove_header = "Subject"
       add_header = Subject: ***SPAM (Score:$spam_score)*** $h_Subject:

_____________________________________________________________


The spamassassin is working, so a mail is denied and not accepted if the score is beyond 200.
And the header with "***SPAM (Score:5.9)***" is generated but only additional!
The remove_headeris ignored - why?

Here you can see the complete result from an actual spam mail.
My Thunderbird only shows the original subject without the "***SPAM" remark.

The examples in the exim wiki are not detailed enough to solve the problem.
https://wiki.debian.org/Exim#Spam_scanning
Where can i find the explanation of the commands for add_header, remove_header in this context?

I would be glad for some help.

_____________________________________________________________

Message-ID: <f90101d25c00$82c3a160$72ec1850@assaxwj>
Reply-To: "Apotheke" <assaxwj@???>
From: "Apotheke" <assaxwj@???>
To: <florian@???>
Subject: Generika kaufen. Schnellversand
Date: Thu, 22 Dec 2016 03:07:21 +0200
MIME-Version: 1.0
Content-Type: multipart/related;
    type="multipart/alternative";
    boundary="----=_NextPart_000_0006_01D25C00.341E44C0"
X-Priority: 3
X-MSMail-Priority: Normal
X-Mailer: Microsoft Windows Live Mail 14.0.8117.416
X-MimeOLE: Produced By Microsoft MimeOLE V14.0.8117.416
X-Sender-Verify: SUCCEEDED (sender exists & accepts mail)
X-ACL-Warn: X-Spam-Score  : 5.9 (+++++)
X-Spam-Score-Int: 59
X-ACL-Warn: X-Message-Age : 0
Subject: ***SPAM (Score:5.9)*** Generika kaufen. Schnellversand