I can't copy a site because it requires authentication but the username is an
email. It is possible to do that but the username and password are separated
from the website address by a "@", as the username is an email it already has
that symbol then the program doesn't work. How can I save that site?
In FAQ section they say the way you have to save a site with password
authentication is like this:

<http://username:password@www.someweb.com/example.html>

I'm using firefox 24.0 win 7 home premium, service pack 1

Many thanks