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diff --git a/src/mailman/rules/suspicious.py b/src/mailman/rules/suspicious.py
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+# 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/>.
+
+"""The historical 'suspicious header' rule."""
+
+from __future__ import absolute_import, unicode_literals
+
+__metaclass__ = type
+__all__ = [
+    'SuspiciousHeader',
+    ]
+
+
+import re
+import logging
+
+from zope.interface import implements
+
+from mailman.i18n import _
+from mailman.interfaces.rules import IRule
+
+log = logging.getLogger('mailman.error')
+
+
+
+class SuspiciousHeader:
+    """The historical 'suspicious header' rule."""
+    implements(IRule)
+
+    name = 'suspicious-header'
+    description = _('Catch messages with suspicious headers.')
+    record = True
+
+    def check(self, mlist, msg, msgdata):
+        """See `IRule`."""
+        return (mlist.bounce_matching_headers and
+                has_matching_bounce_header(mlist, msg))
+
+
+
+def _parse_matching_header_opt(mlist):
+    """Return a list of triples [(field name, regex, line), ...]."""
+    # - Blank lines and lines with '#' as first char are skipped.
+    # - Leading whitespace in the matchexp is trimmed - you can defeat
+    #   that by, eg, containing it in gratuitous square brackets.
+    all = []
+    for line in mlist.bounce_matching_headers.splitlines():
+        line = line.strip()
+        # Skip blank lines and lines *starting* with a '#'.
+        if not line or line.startswith('#'):
+            continue
+        i = line.find(':')
+        if i < 0:
+            # This didn't look like a header line.  BAW: should do a
+            # better job of informing the list admin.
+            log.error('bad bounce_matching_header line: %s\n%s',
+                      mlist.real_name, line)
+        else:
+            header = line[:i]
+            value = line[i+1:].lstrip()
+            try:
+                cre = re.compile(value, re.IGNORECASE)
+            except re.error as error:
+                # The regexp was malformed.  BAW: should do a better
+                # job of informing the list admin.
+                log.error("""\
+bad regexp in bounce_matching_header line: %s
+\n%s (cause: %s)""", mlist.real_name, value, error)
+            else:
+                all.append((header, cre, line))
+    return all
+
+
+def has_matching_bounce_header(mlist, msg):
+    """Does the message have a matching bounce header?
+
+    :param mlist: The mailing list the message is destined for.
+    :param msg: The email message object.
+    :return: True if a header field matches a regexp in the
+        bounce_matching_header mailing list variable.
+    """
+    for header, cre, line in _parse_matching_header_opt(mlist):
+        for value in msg.get_all(header, []):
+            if cre.search(value):
+                return True
+    return False