Need to have Out-of-Office responses sent if one of the members of the Distribution Groups is OoO? By default – if an email is sent to a disribution group, and even if that group only contains 1 member who sets OoO to ON – a automatic response will not be sent.

To enable this feature the distribution group needs to have “Send out-of-office message to originator” enabled. To find this option :

Exchange Management Console > Distribution Group Properties > Advanced Tab