Messages stuck in queues

Hi Gurus,

The process flow of the scenario configured is 3rd party application->PI->SAP ECC.

The message is sent from 3rd application to PI using sender SOAP adapter . After the mappings the message is routed to SAP ECC using inbound proxy and processed in SAP system.

If the SAP ECC is not available where does the message gets stuck... is it in PI outbound queues...does it throw any error in SXMB_MONI in PI...

I need to create some alerts that should be triggered in PI if the SAP ECC is not available.

Could you please advise how I can handle this situation.

Thanks,

Jay.