* tools/hook-scripts/mailer/mailer.py
  (MailedOutput.mail_headers): Modularize the code which encodes
    header value tokens, and use it for encoding both the Subject: and
    From: lines as necessary.

Index: tools/hook-scripts/mailer/mailer.py
===================================================================
--- tools/hook-scripts/mailer/mailer.py	(revision 1407458)
+++ tools/hook-scripts/mailer/mailer.py	(working copy)
@@ -228,12 +228,18 @@
       self.reply_to = self.reply_to[3:]
 
   def mail_headers(self, group, params):
-    subject = self.make_subject(group, params)
-    try:
-      subject.encode('ascii')
-    except UnicodeError:
-      from email.Header import Header
-      subject = Header(subject, 'utf-8').encode()
+
+    def _maybe_encode_header(hdr):
+      try:
+        hdr.encode('ascii')
+        return hdr
+      except UnicodeError:
+        from email.Header import Header
+        return Header(hdr, 'utf-8').encode()
+
+    subject = ' '.join(map(_maybe_encode_header,
+                           self.make_subject(group, params).split()))
+    from_hdr = ' '.join(map(_maybe_encode_header, self.from_addr.split()))
     hdrs = 'From: %s\n'    \
            'To: %s\n'      \
            'Subject: %s\n' \
@@ -244,7 +250,7 @@
            'X-Svn-Commit-Author: %s\n' \
            'X-Svn-Commit-Revision: %d\n' \
            'X-Svn-Commit-Repository: %s\n' \
-           % (self.from_addr, ', '.join(self.to_addrs), subject,
+           % (from_hdr, ', '.join(self.to_addrs), subject,
               group, self.repos.author or 'no_author', self.repos.rev,
               os.path.basename(self.repos.repos_dir))
     if self.reply_to: