How to Remove X-headers

[Glenn]

We use MailScanner and Postfix on a mail gateway server and forward mail to 
an internal Microsoft Exchange 2003 server.  Evidently, enough X-headers have 
accumulated in an Exchange database to cause a problem, so we need to remove 
X-headers before they are forwarded to the Exchange server.

There is a line in MailScanner.conf that allows us to name whatever headers 
we want to remove ("Remove These Headers"), but this raises some questions.  
If we just blanket remove all X-headers, won't this defeat features of 
MailScanner that depend on MailScanner adding headers?

According to hints in the MailScanner rules directory, we should be able to 
use regular Perl expresssions to create a ruleset to exclude certain headers 
from the delete list.  My problem is that I don't have a clue how to write 
regular Perl expressions.  From what I've read online, for example, the lines 
below should be equivalent, but when I use the Perl expression in the ruleset 
it doesn't work.

From:  [ipaddress]  X-MimeOLE:    ##this removes the X-MimeOLE header

From:  [ipaddress]  /^XMime.*\:/  ##this doesn't

I know this isn't a Perl forum, but I'm hoping that someone who has tried 
this can enlighten me.  If I could just get a simple expression to work, I 
might be able to build what I need.  Thanks.   -Glenn.