You
should be able to log into your Orange email account via this link:
http://email.orange.co.uk/
However my browser (Firefox) is reporting that the site's security certificate is out of date. If you experience the same problem it's probably safe to allow your browser to override the warning but it definitely seems to indicate that EE are no longer interested in supporting old Orange email addresses.
So it might be best to look for a new email account. The service that's incredibly popular with AB members (probably, in part, because I love it and constantly promote it here!) is GMX:
http://www.gmx.co.uk/
(Simply click 'Free Sign Up' and follow the instructions. It's dead easy!)