Spoilers

Get a list of users per role

$result = db_query('SELECT * FROM users u INNER JOIN users_roles ur 
ON u.uid = ur.uid WHERE ur.rid = :rid', array('rid' => 3));
$users = $result->fetchAll();
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Get the site email address

$site_email_address = variable_get('site_mail', '');
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Use a placeholder to get the user's name in the mail

$email_message = t('Hello @name, a new article has been posted', array('@name' => $user->name));
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Enable mail logging on Windows: http://drupal.org/node/625062#comment-4641292 Edit sites/default/settings.php and add that snippet. Look in sites/default/files/temporary for the mails, they will be logged to text files.