Add notes to whatsnew porting for visible changes in email compatibility mode.
diff --git a/Doc/whatsnew/3.3.rst b/Doc/whatsnew/3.3.rst
index 1943a06..4e62595 100644
--- a/Doc/whatsnew/3.3.rst
+++ b/Doc/whatsnew/3.3.rst
@@ -2102,6 +2102,22 @@
special case the standard import hooks so they are still supported even
though they do not provide the non-standard ``iter_modules()`` method.
+* A longstanding RFC-compliance bug (:issue:`1079`) in the parsing done by
+ :func:`email.header.decode_header` has been fixed. Code that uses the
+ standard idiom to convert encoded headers into unicode
+ (``str(make_header(decode_header(h))``) will see no change, but code that
+ looks at the individual tuples returned by decode_header will see that
+ whitespace that precedes or follows ``ASCII`` sections is now included in the
+ ``ASCII`` section. Code that builds headers using ``make_header`` should
+ also continue to work without change, since ``make_header`` continues to add
+ whitespace between ``ASCII`` and non-``ASCII`` sections if it is not already
+ present in the input strings.
+
+* :func:`email.utils.formataddr` now does the correct content transfer
+ encoding when passed non-``ASCII`` display names. Any code that depended on
+ the previous buggy behavior that preserved the non-``ASCII`` unicode in the
+ formatted output string will need to be changed.
+
Porting C code
--------------