I currently us zapier.com to receive form data from webflow and send the email to the user from there.
This is my workflow
Connect you webflow project to you zapier account.
In your form add an embed widget and add some hidden data like email address contact name ect…
<input type="hidden" value="Email address " name="Email" />
Setup a zap with zapier email to collect the form data and configure so it will use the hidden email on the form to send the email.
You can also make a form work with the cms by binding cms data in you hidden fields inside of the embed widget.