So, I solve the problem by a strange way .... I had configure a destination set in ISA for my exchanger server with the paths /exchange/*,/exchweb/* and /public/* with the name "mail" . Then, I created a new publishing rule using the destination set "mail" with a redirection to my exchange server but that was not working. So, I created a new publishing rule. In the destination set, I set to "all destinations" and for the redirection, my exchange server. Now, I can access OWA throught internet. I know this is not the good solution but that's the only one I founded (after 1 week of research). If someone can tell me why is it not working with my destination set "email", I'll appreciate. Thanks to all Arnaud