[Mailman-Users] 403 Forbidden - You don't have permission to access /pipermail/

[Andrew Steele]

I have discovered that our mailman installation returns a 403 
Forbidden error when trying to access archives from the web pages.

The links all point, correctly, to 
http://airedale.cnet.org/pipermail/list_name

Accessing that URL returns a message stating:

Forbidden

You don't have permission to access /pipermail/list_name on this 
server.

If I, instead, access the URL http://airedale.cnet.org/pipermail/ a 
directory listing is displayed showing the archive files by name.

I have checked that the archives are set to be public.

Is there a setting I need to add to a configuration somewhere that 
someone can point me to?  I have seen a similar question posed in the 
list archives but not seen any pointer to a solution.

Andrew