The Reference header isn't even produced here. If this is right out of
your incoming packet, then your host isn't sending correct headers --
quite possibly due to too long a references line.
> E@wse.com> <01bbc9fe$0b734340$90995ccf@default> <327E2D68.446B@wse.com> <3281512
It starts out in the middle of one of the references and doesn't even
have the References: heading. (I'm assuming that's how it came because
your sample had other headers intact).
YARN is handling long reference lines just fine for me. It's uqwk that's
rejecting them as 'too long' (but not munged though).
Check the same message from online and see if the reference line is
messed up on your host. If not, uqwk or whatever you're using may be to
blame.