Deae Friend

I have observed a strange behaviour on some web sites.

Let's suppose that my browser (mostly I use Firefox) is
visualizing the page dogs@somesite.com. That page contains a link to
cats@somesite.com and it works fine: when I click
on the link my browser really moves to cats@somesite.com.

But when I store the link cats@somesite.com in a plain text
file for later use, pasting it in the addres bar of the
browser makes me get, no more cats@somesite.com as did before, a warning about
a processing request failure, instead.

When I try to get cats@somesite.com by means of winhttrack
the only achieve is a page not found message.

Please, can anyone elucidate the web site comportment and, if possible,
suggest a workaround for winhttrack use ?
Thanks for your attention.
Warmest regards

Scintilla