diff -up mailman-2.1.9/Mailman/Queue/Runner.py.backup mailman-2.1.9/Mailman/Queue/Runner.py
--- mailman-2.1.9/Mailman/Queue/Runner.py.backup	2009-10-20 14:33:03.000000000 +0200
+++ mailman-2.1.9/Mailman/Queue/Runner.py	2009-10-20 14:33:55.000000000 +0200
@@ -98,7 +98,7 @@ class Runner:
                 # Ask the switchboard for the message and metadata objects
                 # associated with this filebase.
                 msg, msgdata = self._switchboard.dequeue(filebase)
-            except email.Errors.MessageParseError, e:
+            except Exception, e:
                 # It's possible to get here if the message was stored in the
                 # pickle in plain text, and the metadata had a _parsemsg key
                 # that was true, /and/ if the message had some bogosity in
@@ -106,7 +106,8 @@ class Runner:
                 # There's not much we can do (and we didn't even get the
                 # metadata, so just log the exception and continue.
                 self._log(e)
-                syslog('error', 'Ignoring unparseable message: %s', filebase)
+                syslog('error', 'Skipping and preserving unparseable message: %s', filebase)
+                self._switchboard.finish(filebase, preserve=True)
                 continue
             try:
                 self._onefile(msg, msgdata)
@@ -121,9 +122,14 @@ class Runner:
                 self._log(e)
                 # Put a marker in the metadata for unshunting
                 msgdata['whichq'] = self._switchboard.whichq()
-                new_filebase = self._shunt.enqueue(msg, msgdata)
-                syslog('error', 'SHUNTING: %s', new_filebase)
-                self._switchboard.finish(filebase)
+                try:
+                    new_filebase = self._shunt.enqueue(msg, msgdata)
+                    syslog('error', 'SHUNTING: %s', new_filebase)
+                    self._switchboard.finish(filebase)
+                except Exception, e:
+                    self._log(e)
+                    syslog('error','SHUNTING FAILED, preserving original entry: %s', filebase)
+                    self._switchboard.finish(filebase, preserve=True)
             # Other work we want to do each time through the loop
             Utils.reap(self._kids, once=True)
             self._doperiodic()
diff -up mailman-2.1.9/Mailman/Queue/Switchboard.py.backup mailman-2.1.9/Mailman/Queue/Switchboard.py
--- mailman-2.1.9/Mailman/Queue/Switchboard.py.backup	2009-10-20 14:33:22.000000000 +0200
+++ mailman-2.1.9/Mailman/Queue/Switchboard.py	2009-10-20 14:33:48.000000000 +0200
@@ -164,12 +164,24 @@ class Switchboard:
             msg = email.message_from_string(msg, Message.Message)
         return msg, data
 
-    def finish(self, filebase):
+    def finish(self, filebase, preserve=False):
         bakfile = os.path.join(self.__whichq, filebase + '.bak')
         try:
-            os.unlink(bakfile)
+            if preserve:
+                psvfile = os.path.join(mm_cfg.SHUNTQUEUE_DIR, filebase + '.psv')
+                omask = os.umask(0)                       # rwxrws---
+                try:
+                    try:
+                        os.mkdir(mm_cfg.SHUNTQUEUE_DIR, 0770)
+                    except OSError, e:
+                        if e.errno <> errno.EEXIST: raise
+                finally:
+                    os.umask(omask)
+                os.rename(bakfile, psvfile)
+            else:
+                os.unlink(bakfile)
         except EnvironmentError, e:
-            syslog('error', 'Failed to unlink backup file: %s', bakfile)
+            syslog('error', 'Failed to unlink/preserve backup file: %s', bakfile)
 
     def files(self, extension='.pck'):
         times = {}