TMDA and TCPSERVER: Whitelist IP addresses?

I have an install of a qmail POP toaster according to the instructions
at http://shupp.org/toaster including TMDA.  So far, everything seems
to be working fine.  I have only one "feature" I need to happen before
I can unveil it to my users.  I need to have TMDA not quarantine
messages that are submitted from a contact form on our website.  In
essence, I need to whitelist the IP address of our webserver.  I had
originally hoped to be able to just whitelist "[email protected]"
(the Apache user) but the form uses the visitor's email address as the
from: address.

I thought maybe the easiest way to do this would be to add a rule to
tcpserver that would set an environment variable that TMDA would
recognize and it would just pass it through.  Kind of like how you set
RELAYCLIENT="" to allow IPs to relay through the server.

Is there anything like this in TMDA?  or is there any other way of doing this?

Thanks!
-ken
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