compare 2 headers

[Lawrence @ Rogers]

Hi,

Is there a quick way to compare 2 headers? I am seeing spam lately that 
has an invalid e-mail address (one not hosted by us) set in the To: 
header, but has the intended one in the Envelope-To: header

What I would like to do is take the Envelope-To and run a regex to check 
if the To: header contains it.

Is this possible?

Regards,

Lawrence Williams
LCWSoft