Transform a input json to { "Name": ["John Doe"], "Email": ["[email protected]"],"Address": ["123 Willow Dr, San Jose, CA"]}

Question

How Do i transform this line from { "Name": ["John Doe"], "Email": ["[email protected]"],"Address": ["123 Willow Dr, San Jose, CA"]} to this

 { "Name": ["John Doe"], "Email": ["John_Doe"],"Address": ["123 Willow Dr, San Jose, CA"]}.

Replace the domain name with spaces if exists. The input json may or may not have @User.opa.com.

I tried to apply reg_ex match, I dont think I am getting the right results.