Checkpointing for refactoring.

1 files changed, 19 insertions, 8 deletions

diff --git a/src/mailman/interfaces/bounce.py b/src/mailman/interfaces/bounce.py
index fba269609..60c162bb2 100644
--- a/src/mailman/interfaces/bounce.py
+++ b/src/mailman/interfaces/bounce.py
@@ -21,18 +21,28 @@ from __future__ import absolute_import, unicode_literals
 
 __metaclass__ = type
 __all__ = [
+    'BounceStatus',
     'IBounceDetector',
-    'NonFatal',
     ]
 
 
+from flufl.enum import Enum
 from zope.interface import Interface
 
 
 
-# Matching addresses were found, but they were determined to be non-fatal.  In
-# this case, processing is halted but no bounces are registered.
-NonFatal = object()
+class BounceStatus(Enum):
+    """Special bounce statuses."""
+
+    # Matching addresses were found, but they were determined to be non-fatal.
+    # In this case, processing is halted but no bounces are registered.
+    non_fatal = 1
+
+    # If a bounce detector returns Stop, that means to just discard the
+    # message.  An example is warning messages for temporary delivery
+    # problems.  These shouldn't trigger a bounce notification, but we also
+    # don't want to send them on to the list administrator.
+    stop = 2
 
 
 
@@ -45,8 +55,9 @@ class IBounceDetector(Interface):
         :param msg: An email message.
         :type msg: `Message`
         :return: The detected bouncing addresses.  When bouncing addresses are
-            found but are determined to be non-fatal, the special marker
-            `NonFatal` can be returned to halt any bounce processing
-            pipeline.  None can be returned if no addresses are found.
-        :rtype: A sequence of strings, None, or NonFatal.
+            found but are determined to be non-fatal, the enum
+            `BounceStatus.non_fatal` can be returned to halt any bounce
+            processing pipeline.  When bounce processing should stop, a
+            `BounceStatus.stop` is returned.
+        :rtype: A set strings, or a `BounceStatus`
         """