Ils sont marrant les codes de retour des serveurs SMTP d'AOL :

550 We would love to have gotten this email to mamanours@aim.com. 
    But, your recipient never logged onto their free AIM Mail account. 
    Please contact them and let them know that they're missing out on 
    all the super features offered by AIM Mail. And by the way, 
    they're also missing out on your email. Thanks.