invalid header: all-whitespace header field

[Justin Cantrell]

I have a Debian Squeeze mail server that was recently updated from Etch 
> Lenny > Squeeze. After the updates amavis is sending messages to 
quarantine. I can't seem to figure out why!

Error: INVALID HEADER: FOLDED HEADER FIELD MADE UP ENTIRELY OF WHITESPACE
My /etc/amavis/conf.d/50-user has
$final_bad_header_destiny = D_PASS;
$bad_header_quarantine_to = undef;

So it SHOULD be passing them. Any idea on what is going on here?

Other info. Running Postfix/Dovecot with Amavis/Clam/Spamassassin.