How to stop triggering output message while doing the confirmation of PO

We are having problem in triggering output message to Vendor while doing the confirmation of the PO.

Our requirement is when ever confirmation is being entered in the already created PO, output message should not be generated. Present scenario is Output message is getting triggered successfully when we create PO and One more output message is getting triggered successfully when we enter the confirmation control key in the PO later stage. We want to stop the second output message to trigger when ever we enter the confirmations in the PO.

Below are the technical details of the Output messages:

Output type: NEU

Medium : A (Distribution ALE)

Regards

qsm sap