Hi user12557,
Currently there is no feature for your customers to 'click and accept' or similar when receiving quotes, although I can see how this would be a useful tool and would be happy to pass this suggestion along for consideration in a future product enhancement. As a workaround, your clients could reply to the email to advise they accept the quote and this will go to the email you have set up to be customer-facing in your settings. You could then attach the email to the invoice when converted to a quote, or so on. To confirm which email address this will be received to:
-Kass