1 files changed, 48 insertions, 0 deletions
diff --git a/src/mailman/rules/loop.py b/src/mailman/rules/loop.py
new file mode 100644
index 000000000..564d20dc6
--- /dev/null
+++ b/src/mailman/rules/loop.py
@@ -0,0 +1,48 @@
+# Copyright (C) 2007-2009 by the Free Software Foundation, Inc.
+#
+# This file is part of GNU Mailman.
+#
+# GNU Mailman is free software: you can redistribute it and/or modify it under
+# the terms of the GNU General Public License as published by the Free
+# Software Foundation, either version 3 of the License, or (at your option)
+# any later version.
+#
+# GNU Mailman is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# GNU Mailman.  If not, see <http://www.gnu.org/licenses/>.
+
+"""Look for a posting loop."""
+
+from __future__ import absolute_import, unicode_literals
+
+__metaclass__ = type
+__all__ = [
+    'Loop',
+    ]
+
+
+from zope.interface import implements
+
+from mailman.i18n import _
+from mailman.interfaces.rules import IRule
+
+
+
+class Loop:
+    """Look for a posting loop."""
+    implements(IRule)
+
+    name = 'loop'
+    description = _('Look for a posting loop, via the X-BeenThere header.')
+    record = True
+
+    def check(self, mlist, msg, msgdata):
+        """See `IRule`."""
+        # Has this message already been posted to this list?
+        been_theres = [value.strip().lower()
+                       for value in msg.get_all('x-beenthere', [])]
+        return mlist.posting_address in been_theres