Whenever you are checking your emails for the first time from a particular web browser, you will remember having seen the standard Hotmail Sign in, as depicted with the form in the screenshot below, which offers a "Remember me" option, discussed on this page, and another setting to memorize your password, discussed in another tutorial (When to make Hotmail remember your password). Once you have gotten into the habit of checking your emails from the same place, you will likely not see the login form very often, and made Hotmail automatically remember your email address and/or password by default. Let's see how safe this option is for various security scenarios.
Since all situations are different, the easiest way to help you evaluate the safety of making Windows Live Hotmail automatically sign you in, or at least remember your email address.
As soon as you click on the "Sign in" button, Hotmail will check your credentials (correct email address / password combination). If you checked the "Remember me" checkbox, it will create a "cookie" on your computer: this is a small text file that contains some information that a certain website can access at a later stage (
www.hotmail.com in our case). Here is a cookie set to remember our account information, viewed from our web browser's cookie manager:
As you can tell from the picture above, the information is stored in a "gibberish" form, that means little to most of us. But this information can be used throughout the Hotmail login process to determine if the Windows Live website should show you a blank sign in form, a (partially or not) filled-in form, or if it should directly send you to your inbox or the Windows Live Home page.
So, the content of the cookie created by Windows Live for your Hotmail account itself is safe from most prying eyes, but the security ultimately boils down to how secure access to your computer and/or browser is. If someone has access to your computer, or has your Windows / Mac password, they can automatically login to your Hotmail account and read your email messages - if you only chose "Remember me", and left "Remember my password" unchecked, that person will not go far if they do not know your password.
As discussed in details in "Hotmail Sign in from a public computer", you should always make your choice based on common sense: there is always a trade-off between convenience and security. We recommend that you take a couple of minutes to read that tutorial if you ever login to your Hotmail account from a computer other than your own (this includes work, school, a public library, or other unfamiliar places).