To anyone who has Exchange 2007 on a Windows Small Business Server 2008 - SBS only has Mailbox, ClientAccess, HubTransport roles - no Edge. Apparently, the Hub Transport server (misleadingly) has the same settings, but will bounce the messages with a 5.1.1 NDR, even if you disable recipient filtering. The solution/workaround is to use this custom agent assemblyhttp://catchallagent.codeplex.com/releases/view/9982It is also mentioned in this post:http://social.technet.microsoft.com/forums/en-US/ex
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