In SQL Server 2005, calling sp_send_dbmail to send an email sends successfully to an individual's email address, and the message is delivered to the recipient. But if I specify an address which is a distribution group (say firstname.lastname@example.org), although the sp returns 0 the message is not delivered to any of the recipients. I'm told by the person who looks after our Exchange server (we are running Exchange 2010 SP1) that he can't find anything in the Exchange logs for the undelivered messages. Exchange is configured to allow mail from the IP address of the server on which SQL Server resides (and of course some messages sent through sp_send_dbmail are delivered). I've examined the logs and queried for message status and they state all messages have been sent and queues are working.
Thanks for any help.