How to trigger “return receipt”?

Hello,

I love CF7 and I use it for years, but now I got stuck.

I made a simple request for pricing form, and what I would like to do, is to make the system prompt my mail server (the recipient of the RFP) send automated confirmation (the read receipt) to the Reply-to address.
I do not need any specific message – just a confirmation it was received.

I can script it at the client level , but having server sort it out would be obviously better.
Any suggestion how to achieve it, please?

P.

The page I need help with: [log in to see the link]