Unordered delivery (IXCMSGOX DELIVERMSG=UNORDERED) is the default mode and means that messages can be delivered in any order, regardless of the order in which they were sent. The delivery of unordered messages might even be interspersed among messages for which ordered delivery was requested.

Unordered delivery occurs if a message is sent to a target member that resides on a system that does not support ordered message delivery.