How to use the SharePoint Client Object Model to get the email address of each user with access to a list

Here's what I have so far:

        private static bool RoleAssignmentHasPermissions(RoleAssignment roleAssignment)
        {
            roleAssignment.Context.Load(roleAssignment.RoleDefinitionBindings);
            roleAssignment.Context.ExecuteQuery();

            foreach (var x in roleAssignment.RoleDefinitionBindings)
            {
                if (x.BasePermissions != null)
                    return true;
            }

            return false;
        }

        foreach (RoleAssignment x in MyListItem.RoleAssignments)
        {
                MyListItem.Context.Load(x.Member);
                MyListItem.Context.ExecuteQuery();

                bool hasPermissions = RoleAssignmentHasPermissions(x);

                if (x.Member is Group)
                {
                    // For groups, recursively process the user entries.
                    foreach (User u in ((Group)x.Member).Users)
                    {
                        // get user's email address
                    }
                }
                else
                {
                    // For users, directly, process entry.
                    // get user's email address
                }
         }