Use of RFC LookUp

Hi

Sending EDIFACT file(Source system) to SAP(Target System -Idoc)

I have requirement like this There is new function moduel ZXX_XXXX developed in sap (target system)

I need to work on RFClookup by using this newly developed function module in my message mapping .

function Module contains Importing 5 parameters, exporting one sy-SubRC parameter.

If the result is sy-subrc = 4

This is the normal situation and the order / idoc should be generated

as normally.

If the result is sy-subrc = 0

Now we are in a situation where we earlier have received this order.

Instead of generation an IDOC, an email must be send to: xxx

Note : BPM can also use

Pls let me know how to proceed.

- Ramesh