A volte è meglio andare alla fonte
Hello Wisher,

Thank you for the kind comments on my AJAX article. I’m glad you liked it. Concerning your question, you’re correct. If you use Firefox, its security model won’t let you trigger cross-domain requests. However, IE 6 will only display a warning in that case, and let you choose what to do. This could be used to send unwanted requests to many sites or even simulate genuine form submissions.
Also, there are a few other techniques to send http requests, like JavaScript boot loaders, but it’s a bit more complex than using AJAX.
Again, thank you for your comments and Season's Greetings to you.

Alejandro Gervasio
Era proprio quello che stavo cercando.