Patch to prevent browser from caching pages.
Index: Mailman/htmlformat.py
===================================================================
--- Mailman/htmlformat.py.orig	2006-09-19 13:43:51.000000000 +0200
+++ Mailman/htmlformat.py	2006-09-19 15:47:16.000000000 +0200
@@ -300,7 +300,8 @@
         charset = 'us-ascii'
         if self.language and Utils.IsLanguage(self.language):
             charset = Utils.GetCharSet(self.language)
-        output = ['Content-Type: text/html; charset=%s\n' % charset]
+        output = ['Content-Type: text/html; charset=%s' % charset]
+        output.append('Cache-control: no-cache\n')
         if not self.suppress_head:
             kws.setdefault('bgcolor', self.bgcolor)
             tab = ' ' * indent