1 files changed, 37 insertions, 0 deletions
diff --git a/src/mailman/interfaces/chain.py b/src/mailman/interfaces/chain.py
index 8858f874c..8862026f8 100644
--- a/src/mailman/interfaces/chain.py
+++ b/src/mailman/interfaces/chain.py
@@ -21,11 +21,17 @@ from __future__ import absolute_import, unicode_literals
 
 __metaclass__ = type
 __all__ = [
+    'AcceptEvent',
+    'AcceptOwnerEvent',
+    'ChainEvent',
+    'DiscardEvent',
+    'HoldEvent',
     'IChain',
     'IChainIterator',
     'IChainLink',
     'IMutableChain',
     'LinkAction',
+    'RejectEvent',
     ]
 
 
@@ -34,6 +40,37 @@ from zope.interface import Interface, Attribute
 
 
 
+class ChainEvent:
+    """Base class for chain notification events."""
+
+    def __init__(self, mlist, msg, msgdata, chain):
+        self.mlist = mlist
+        self.msg = msg
+        self.msgdata = msgdata
+        self.chain = chain
+
+
+class AcceptEvent(ChainEvent):
+    """A notification event signaling that a message is being accepted."""
+
+
+class AcceptOwnerEvent(ChainEvent):
+    """An event signaling that a message is accepted to the -owner address."""
+
+
+class DiscardEvent(ChainEvent):
+    """A notification event signaling that a message is being discarded."""
+
+
+class HoldEvent(ChainEvent):
+    """A notification event signaling that a message is being held."""
+
+
+class RejectEvent(ChainEvent):
+    """A notification event signaling that a message is being rejected."""
+
+
+
 class LinkAction(Enum):
     # Jump to another chain.
     jump = 0