When an email is sent from Propose to your client by default, it is sent directly by Propose, so the email address will appear with our email domain and will be a no-reply address. 

However, you can set your SMTP details to send these emails from your address instead to allow responding, to do this please navigate to Settings > Email Settings to the location shown below.

To change this please click Send outgoing emails from my business email address and then fill out the details in the below sections, you can find your email providers SMTP details online.

Once done make sure to Save Changes.