note 11595 added to array

I named a cookie by email address in a script I was writing and then tried to access it using $http_cookie_vars['emailadr@domain.cxm'] and many permutations of this. Php 4pl1 did not go for this at all and after many hours of trying stupid things that I knew wouldn't work anyway I came to realise that it was the "." that php wasn't accepting. I was wondering why this is and if there is any way around it? Thanks in advance. Rob! http://www.php.net/manual/en/function.array.php