<html> <head> </head> <body> <h1> 404 - Page not found </h1> collect.e.mail-serv.co.uk </body> </html>
You can type viewhtmlonline.com in front of any url you're browsing and it will show you the source.
viewhtmlonline.com
For example: viewhtmlonline.com/https://temp.cool
viewhtmlonline.com/https://temp.cool