3 files changed, 13 insertions, 1 deletions
diff --git a/src/mailman/interfaces/action.py b/src/mailman/interfaces/action.py
index c7c79f7d8..9b3c1fbcc 100644
--- a/src/mailman/interfaces/action.py
+++ b/src/mailman/interfaces/action.py
@@ -20,6 +20,7 @@
 __metaclass__ = type
 __all__ = [
     'Action',
+    'FilterAction',
     ]
 
 
@@ -33,3 +34,8 @@ class Action(Enum):
     discard = 2
     accept  = 3
     defer   = 4
+
+
+class FilterAction(Action):
+    forward = 5
+    preserve = 6
diff --git a/src/mailman/interfaces/handler.py b/src/mailman/interfaces/handler.py
index f9a075b8c..9007e8490 100644
--- a/src/mailman/interfaces/handler.py
+++ b/src/mailman/interfaces/handler.py
@@ -17,7 +17,7 @@
 
 """Interface describing a pipeline handler."""
 
-from __future__ import absolute_import, unicode_literals
+from __future__ import absolute_import, print_function, unicode_literals
 
 __metaclass__ = type
 __all__ = [
diff --git a/src/mailman/interfaces/mailinglist.py b/src/mailman/interfaces/mailinglist.py
index a3e6e443a..843430caf 100644
--- a/src/mailman/interfaces/mailinglist.py
+++ b/src/mailman/interfaces/mailinglist.py
@@ -423,6 +423,12 @@ class IMailingList(Interface):
         Filtering is performed on MIME type and file name extension.
         """)
 
+    filter_action = Attribute(
+        """Action to take when the top-level content-type is filtered.
+
+        The value is a `FilterAction` enum.
+        """)
+
     convert_html_to_plaintext = Attribute(
         """Flag specifying whether text/html parts should be converted.