As you would probably expect, I am a member of a number of email discussion lists based around Microsoft Exchange. These include the lists at Sunbelt Software, msexchange.org (via freelists), Swinc.com and some others.
However what always surprises me is the number of Out of the Office (OOTO) messages that I get from these lists when I make a post.
As Exchange admins they should be able to use distribution lists in a way that ensures OOTO messages do not get returned to list members. This can also ensure that internal information is not broadcast to a large number of strangers. I have talked about the security concerns of OOTO messages before (http://blog.sembee.co.uk/archive/2006/06/08/Out-of-Office-Messages-to-the-Internet.aspx).
At a minimum, if you are using Exchange 2003, then you should look to make the OOTO suppression registry change as outlined here: http://support.microsoft.com/default.aspx?kbid=825370
However the easiest way I have found to work with discussion lists is to use public folders.
Each list gets its own public folder. This public folder is mail enabled. The list is subscribed to using the email address of the public folder. All posts go in to the public folder.
Permissions are configured as required, with at least anonymous having contributor permissions. Everyone else can be hidden by changing the default permissions to none.
To post replies, I subscribe my personal email address, but use the options on the list to "no mail". This could also be listed as a holiday setting or similar wording.
The additional benefit of using a public folder is that more than one person in the company can read the distribution list. New members of staff could also have access to the archives. On my home Exchange server the public folder store is actually bigger than my mailbox store.
One note of caution. If you are using Outlook in cached mode/offline folders, then I would suggest that you do not configure these public folders to be available offline. Many of the large Exchange discussion lists are very high traffic and you may find you are spending a long time waiting for the folders to sync.
Public Folders are not going away for some time, so this method will work for a few years yet. If you have started to use Sharepoint 3.0 then you could do something similar with that, but public folders is very easy to work with for this particular application.