[exim] Rewriting subject with Spamassassin

Hi,

I'm using Spamassassin with a setup as per manual and change the subject with the
following:

warn  message = Subject: [SPAM? $spam_score] $h_Subject:
      spam = nobody

Unfortunately their are mail readers that don't show the second line in the subject.

Is there a way to remove the subject and replace it with the second line only ie

[SPAM? 32.0] The Subject

Thanks

Nico