New Distribution Groups in Exchange 2007 Require Sender Authentication by Default

When a new distribution group is created in Exchange 2007, by default it is set to accept messages only from authenticated senders. A group can be set to not require authentication by using the Set-DistributionGroup command to set RequireSenderAuthenticationEnabled to $False.

To see what groups are set to require authentication, use the following command:

Get-DistributionGroup | where {$_.RequireSenderAuthenticationEnabled -eq $True}

Please note that the default settings also do not permit the object in the "Managed By" field to edit group membership.