--- roundup.orig/rfc2822.py	2005-01-03 03:53:03.000000000 +0100
+++ roundup/rfc2822.py	2006-01-24 18:20:41.865015232 +0100
@@ -141,7 +141,7 @@
         if c == ' ':
             quoted += '_'
         # These characters can be included verbatim
-        elif hqre.match(c):
+        elif hqre.match(c) and c != '_':
             quoted += c
         # Otherwise, replace with hex value like =E2
         else: