Hi Lalith,
We had the same issue of wanting to receive notification once a supplier submits a response. The only way we were able to achieve this was by enabling envelopes as standard for all sourcing events. We just use one envelope for the suppliers entire response.
If you use an envelope in your RFx the project owner is notified as soon as a bid is submitted. We don't need the envelope mechanic for any other purpose (it makes you select all the suppliers and then open the envelope once the event closes) but the pay off of being notified was worthwhile for us to implement.
I'd be interested if there's a way of receiving these notifications without having to use an envelope as that would make for a much cleaner experience from our end.
Regards,
Ollie.