Hi. I have seen the same error several times, mostly with spam.

Attached are two versions of a (kind of minimal) email which provokes
that error. 

They differ by

   diff TTT1 TTT2
   18a19
   > Content-Transfer-Encoding: quoted-printable

The file TTT2 produces the error, while file TTT1 seems to behave well.

Regards
Ulf