Currently we have the below status's for outbound messages:
Queued = 0,
FailRejected = 1,
FailOffline = 2,
Success = 3,
QueuedRetry = 4
Queued is used for two types of messages though. It is used if it is just in the queue waiting for its turn.
It is also used if it is not going to be sent because there is a previously failed message with the same order number. This type of message will not be processed until the failed message is dealt with.