If you need to define default access for Windows Live Users add "liveroles:Validated Live Users" or "liveroles:Authenticated Live Users" to a group that have your desired permisions.
Example 1: You can add "liveroles:Validated Live Users" to "Site Members" group, so any users that enter valid email address will have contribute access to your site.
Example 2: You can add "liveroles:Validated Live Users" to "Site Visitors" group, so any users that enter valid email address will have access to see the sites that anonymous access is disabled.
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