=== modified file 'Mailman/Handlers/CookHeaders.py'
--- Mailman/Handlers/CookHeaders.py	2016-03-02 09:57:16 +0000
+++ Mailman/Handlers/CookHeaders.py	2016-11-20 19:56:22 +0000
@@ -154,12 +154,17 @@
                 realname = email
         # Remove domain from realname if it looks like an email address
         realname = re.sub(r'@([^ .]+\.)+[^ .]+$', '---', realname)
-        # RFC 2047 encode realname if necessary.
-        realname = str(uheader(mlist, realname))
+        # Make a display name and RFC 2047 encode it if necessary.
         lrn = mlist.real_name
+        # realname might already be RFC 2047 encoded.
+        realname, cs = ch_oneline(realname)
+        lcs = Utils.GetCharSet(mlist.preferred_language)
+        if cs != 'us-ascii' and  cs != lcs:
+            realname = realname.decode(cs, errors='replace').encode(lcs,
+                                                             errors='replace')
+        dn = str(uheader(mlist, _('%(realname)s via %(lrn)s')))
         change_header('From',
-                      formataddr((_('%(realname)s via %(lrn)s'),
-                                 mlist.GetListEmail())),
+                      formataddr((dn, mlist.GetListEmail())),
                       mlist, msg, msgdata)
     else:
         # Use this as a flag