Hello,
You didn't answer the "Why???".
Yes, that should be possible, try using fm SAP_WAPI*GET*DETAILS* on a workflow where the mail was sent and see if you can detect it.
Or you could change the process so that it detects whether the Send Mail part was successful before continuing. If in error then stop, or return an error.
I see no reason to try to do this while the process is running, wait until it finishes.
And, as always, don't use a Z table!! (unless you have no other choice)
regards
Rick