How would I go about adding a new Mail Header?

[folta@cs.UMD.EDU (Wayne Folta)]

On our corporate network, we have an extra mail header, "Handling:".
How would I go about adding such a thing to Zmailer? Do I have to
modify the SSL?

I'd like to be able to:

1. Detect the presence of teh Handling field,
2. Place the Handling type into a envelopeinfo when router is called,
3. (Optionally) add a Handling field if none present.

Thanks!

   Wayne