They charge for the 'premium' packages, I think the cheapest is about $25 per year - you get a huge storage limit and don't need to log in once a month.
On the free account they delete your emails and suspend the account if you don't log in once a month.
Edited to add following from MSN website:
Can't access my free account from Microsoft Outlook or Outlook Express
To protect our users from the increasing amount of unsolicited junk e-mail or spam sent from MSN Hotmail accounts through Outlook and Outlook Express, we have reluctantly had to restrict the new use of Outlook and Outlook Express to subscribers only.
By making this feature part of a subscription (which requires a user to provide billing information), we can more effectively manage and put a stop to the abuse of this feature, and help protect you and others from unsolicited mail.
If you purchase a subscription service such as MSN Hotmail Plus, or MSN Premium, you get access to your account from Outlook or Outlook Express, along with many other added features. To see other benefits of upgrading your MSN Hotmail or MSN accounts or to create a new subscription account, visit our
subscription information page.