Index: Lib/email/generator.py
===================================================================
--- Lib/email/generator.py	(revision 81292)
+++ Lib/email/generator.py	(working copy)
@@ -12,7 +12,7 @@
 import warnings
 
 from cStringIO import StringIO
-from email.header import Header
+from email.header import Header, decode_header, make_header
 
 UNDERSCORE = '_'
 NL = '\n'
@@ -160,8 +160,10 @@
                 # the header string is continued with tabs.  It will now be
                 # continued with spaces.  This was reversedly broken before we
                 # fixed bug 1974.  Either way, we lose.
-                print >> self._fp, Header(
-                    v, maxlinelen=self._maxheaderlen, header_name=h).encode()
+                hdr = make_header(decode_header(v),
+                                maxlinelen=self._maxheaderlen, header_name=h)
+                print >> self._fp, hdr.encode()
+
         # A blank line always separates headers from body
         print >> self._fp