diff --git a/Lib/mailbox.py b/Lib/mailbox.py
index 29322ed..2c80a62 100755
--- a/Lib/mailbox.py
+++ b/Lib/mailbox.py
@@ -14,6 +14,9 @@
         self.seekp = 0
         self.factory = factory
 
+    def __iter__(self):
+        return self
+
     def next(self):
         while 1:
             self.fp.seek(self.seekp)
@@ -191,6 +194,9 @@
         self.boxes = map(str, list)
         self.factory = factory
 
+    def __iter__(self):
+        return self
+
     def next(self):
         if not self.boxes:
             return None
@@ -219,6 +225,9 @@
 
         self.boxes = boxes
 
+    def __iter__(self):
+        return self
+
     def next(self):
         if not self.boxes:
             return None