Shoutbox

Taken from Help in Hotmail:

Your account policies
Account activity
Your account becomes inactive if you do not sign in for 30 days, or within the first 10 days after signing up for an account. Once an account becomes inactive, all messages, folders, and contacts are deleted, but the account name is still reserved.
If the account stays inactive for an additional 90 days, it is permanently deleted.

From: Microsoft .NET Passport Privacy Statement
Inactivation and Deletion of Account

Microsoft will delete your .NET Passport account if it remains inactive for an extended period of time. Inactivity is defined as a failure to sign in to your .NET Passport account.

If your .NET Passport account was created in an MSN sponsored domain (i.e. @hotmail.com, @WebTV.net, or @msn.com), your account will be made inaccessible if it remains inactive for 120 days, and any account or profile information you have provided will be deleted. If you have a .NET Passport account that was not created in an MSN sponsored domain, your account will be made inaccessible if it remains inactive for 365 days, and any account or profile information you have provided will be deleted.