Rewrite Header Subject

Hi,

I have customers that need to change their message subject when they received spam. I used to change their user_prefs files including the line:
rewrite_header subject *** Provável SPAM ***.
I saw that this function it's not available at the new version. So I changed in the WHM to Old Style Spam System. I read this is slower than the new one.

There is any other solution?