Thank you Menno for this interesting solution. If I can't resolve the issue using my method, I will try to adapt your solution to my case.

Thanks for the feedback. I tried setting Connect Timeout and Response Timeout as adapter's properties and Reply Code Actions, Retry Interval, and Failure Timeout as Business Operations' properties, in this way: 

Set..Adapter.ConnectTimeout = 15Set..Adapter.ResponseTimeout = 10Set..RetryInterval = 5Set..FailureTimeout = 60Set..ReplyCodeActions = "E=R"

But nothing changes if I modify the parameters, as the BO uses only the values defined in the Production Settings (even if they are all blank).

I tried, but only the message that received a reply is displayed. 

edit. I also tried with the BO parameter "RetryCount", for example: 

$$$TRACE(..RetryCount())

but this property is a boolean variable and so I always get print "1". In the same way, I also tried the methods RetryCountGet(), which always print me "1", and RetryCountLogicalToDisplay(), which always print me "96".

Thank you! Is it possible to set these parameters by code? I need to include many similar Business Operations to contact different entities, and I would like to set default parameters so that I don't have to change them every time I add a new BO.

Thank you! With these settings and with a delay of 12 seconds of the Postman Mock Service, the BO correctly resends the message. However, I can't see the resent messages in the visual trace but only a message, as it happens when the message is not resent. Is there a way to see the resent messages as well or at least to see a warning or a log telling us that the BO is trying to send the message again?