Currently Gnus violates this requirement in RFC 3156 (MIME Security
with OpenPGP):

   implementations MUST make sure that no trailing whitespace is
   present after the MIME encoding has been applied.

Fixing it the obvious way would, however, break the intention of this
change:

2003-10-27  Simon Josefsson  <jas@extundo.com>

	* mm-bodies.el (mm-body-encoding): Don't use QP when message body
	only consists of short lines and ASCII, when
	mm-use-ultra-safe-encoding.  Refer to 'About foo' thread in
	gnus-bug, e.g. <ilullrg4k7p.fsf@extundo.com>, for more discussion.
	This make it possible to pipe the raw RFC 822 message into 'gpg'
	and have the signature work.  Potential problem: what if message
	contain data that would be dash-escaped by OpenPGP
	implementations? Then PGP 2.x might not be able to parse the raw
	RFC 822 message correctly.  If that problem is worth fixing, it
	should be fixed by detecting the situation, instead of applying QP
	to everything.  Based on discussion with "John A. Martin"
	<jam@jamux.com>.

-- 
foo