When the client opens the email if he likes the form email he can press a payment button eg paypal then be sent to the full form details. 

when the client opens the email if he likes the form email he can press a payment button eg paypal then be sent to the full form details. 

I believe you are planning to create an approval workflow. If you are, then please check these related threads:

https://www.jotform.com/answers/401633
https://www.jotform.com/answers/212416

As you can see, this possible by using conditions, email alerts and edit link submissions.

If that is not helpful, let us know so that we can further assist you. I can create a demo form for you if you like. Thank you.