In my organization, we have multiple distribution groups set up. One of these consists of a company wide group to which every internal user belongs to. This is a moderated internal group so messages sent to this, as well as other, groups have to be approved before they are delivered.
The whole reason this became a moderated group was that the group is intended for prevalent company information, not for Joe Moron to send out a company wide e-mail telling everyone about his new bed spread.
Despite the lack of general technical understanding that most users in my org have, some figure out that they can just select all from the GAL or one of the other "all company" address lists that are in Exchange and send to the individual users as opposed to the group.
I am wondering if there is any way to enforce the use of a distribution group inside the org with Exchange 2010. Perhaps some kind of filter or rule in Exchange somewhere that checks if the message is being delivered to every mailbox and it was not sent to a distribution group, or by checking for the number of recipient mailboxes and/or all mailboxes are @domain.com; I am not sure but I figured I would see if anyone has any recommendations.
Modifications to Outlook and/or local workstations are NOT out of the question, it would just have to be something I can accomplish through group policy.
Running Win 2K8 SP2 | Exchange 2010 SP1 | XP/Vista/7 | Outlook 2K7/2010/2011(Mac)
I don't know 2010 very well, but on 2003 I know you can limit the amount of recipients a user can send to at one time. We use that function to accomplish something similar to what you describe: preventing staff from selecting everyone in the address book.