Why would message go into holding status?

Just do not understand under what circumstance would a message go into holding status? I thought they would either fail or go through successfully. Please help me to understand this.


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There are many statuses used by XI.

TO_BE_DELIVERED:

The state of message when it is initially handed over to the Messaging System.

● DELIVERING:

The state of message when it has popped out of the MS queuing system and is in the process of being transmitted across the wire or delivered to an application.

● DELIVERED:

The state of message when it has successfully reached its intended recipient.

● HOLDING:

The state of an EOIO message that cannot be delivered until its predecessors have been delivered.

● NON_DELIVERED:

The state assigned to a message when all attempts (retries) to deliver the message to its recipient have failed.

● FAILED:

The state assigned to a message when an administrator decides to abort sending the message, or when a message could not be delivered due to a fatal exception that cannot be repaired.

● WAITING:

The state of a message that has been attempted to be sent at least once, failed, and is currently waiting for another attempt.