Possible? - Postfix + SASL + Rewrite Headers?

[Adam]

Hello all,

Just a quick, but hopefully simple question that I
can't find the answer to after about an hour of
googling...  Is it possible to rewrite the headers of
an outbound messages through my postfix server if the
user was authenticated w/ sasl?

Just something along the lines of, X-Blah: [IP] User
<login at authaddress.com> OK, mainly just to catch any
users sending spam, etc.

I'm stumped.

Adam

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