--- rfc2822.py-firstpatch	2006-01-24 18:20:41.000000000 +0100
+++ rfc2822.py	2006-01-25 10:35:28.168931116 +0100
@@ -141,7 +141,7 @@
         if c == ' ':
             quoted += '_'
         # These characters can be included verbatim
-        elif hqre.match(c) and c != '_':
+        elif hqre.match(c) and c not in '_=':
             quoted += c
         # Otherwise, replace with hex value like =E2
         else: