In the last episode (Dec 12), Marcus Comstedt (ACROSS) (Hail Ilpalazzo!) @ Pike (-) developers forum said:
For text fields, the example section say that "the rules are slightly different", but give no relevant examples. Can you find a better reference that claims your variant is correct for text fields?
My interpretation is that the only difference between structured fields and regular text is that in structured fields, encoded text inside a comment () can butt up against the parens instead of requiring whitespace.
Unfortunately, only one of the examples in RFC2047 is a text field, and the only whitespace in the text is between two encoded-words (and should be eaten). A couple google searches didn't come up with anything useful, so I started grepping my email archives for examples.
The best I could find is a header from the mutt-dev list (see http://groups.yahoo.com/group/mutt-dev/message/7390?source=1 )
The subject line reads
Subject: change to =?us-ascii?Q?rfc2047=5Fencode=5Fstring?=
, which should be decoded to "change to rfc2047_encode_string". I guess most of the time this issue never comes up, since if your subject is filled with non-ASCII characters, your MUA will end up encoding the entire header instead of only the offending word.