We used to recommend that you increase the security of your Hotmail account by creating a new account, one that you would give to online retailers or other organizations that might send a lot of unwanted email.
Now, if you have a Hotmail account, you can create an alias within your account instead of creating an entirely new account. Mail addressed to your alias will go to a separate folder that you designate. When you’re done with the alias, you can get rid of it.
Whomever you give this address to will not know your real email address. This means less spam and more privacy.
Hotmail lets you create up to five email aliases within your account each year. You can create a different alias for each aspect of your online life. For example, you might have one alias for gaming, one for communicating with old friends, and one for your work life.
For step-by-step instructions, see Aliases in Windows Live Hotmail.