@naveenjr, hmm, not entirely sure if I got your point right. But check if this helps - Can we handle messages in an async manner in Rasa Enterprise? - #2 by ricwo.
In your case, from what I understand you could either send the results back to the user if the user opts for a “wait” option or send out a mail (which will be done asynchronously I believe?) if the user opts for “mail” option. I’m asking you to make the wait option to go asynchronously as well.