Check RFC5322, section 2.2.1 "Unstructured Header Field Bodies".
Semantically, unstructured field bodies are simply to be treated as a
single line of characters with no further processing (except for
"folding" and "unfolding" as described in section 2.2.3).
where 2.2.3 ("Long Header Fields") explains the "folding", e.g.
Subject: This is a test
can be represented as:
Subject: This
is a test
After "This" you have a (quoted) space, not a CR/LF.
In RFC5322 2.2.3 it says;
The process of moving from this folded multiple-line representation
of a header field to its single line representation is called
"unfolding". Unfolding is accomplished by simply removing any CRLF
that is immediately followed by WSP. Each header field should be
treated in its unfolded form for further syntactic and semantic
evaluation. An unfolded header field has no length restriction and
therefore may be indeterminately long.
When the subject was split (folded) they did it correctly, after the CRLF the next line
started with a WSP. So according to 2.2.3 the "unfolding" is accomplished by
simply removing the CRLF turning
Subject: =?UTF-8?B?8J+YsSBTSE9QIE5PVzogR2V0IDAlIElOVEVSRVNUIERlYWxzIHBs?=
=?UTF-8?B?dXMgZXhjbHVzaXZlIHZvdWNoZXJzIHdpdGggU1BheUxhdGVyISDwn5GJ?=
into
Subject: =?UTF-8?B?8J+YsSBTSE9QIE5PVzogR2V0IDAlIElOVEVSRVNUIERlYWxzIHBs?=
=?UTF-8?B?dXMgZXhjbHVzaXZlIHZvdWNoZXJzIHdpdGggU1BheUxhdGVyISDwn5GJ?=
I still don't understand where the extra '?' came from, nor do I see in RFC5322
2.2.3 where it says anything about adding or replacing characters. I am also
still confused by what Wietse said when he confirmed postfix does not add
characters. Then where did the extra '?' come from in the postfix log? How is
it not a bug?
After "This" you have a (quoted) space, not a CR/LF.
I'm not getting your point. Why do you keep talking about a "quoted space"? The
first line ends with CRLF and the second line has to start with a space to indicate it is
a continuation of the previous line (folding). Why are you saying that means an '?' has
to be inserted?
