Voici le message que je reçois par mail, j'ai remplacer l'adresse du destinataire par xxxxxxx@aol.com et mon adresse par yyyyyyy@free.fr :

This is the mail system at host perso1.free.fr.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

                   The mail system

<xxxxxxx@aol.com>: host mailin-01.mx.aol.com[64.12.222.197] said: 421-:
    (RLY:CS4) http://postmaster.info.aol.com/errors/421rlycs4.html  421 SERVICE
    NOT AVAILABLE (in reply to end of DATA command)



Reporting-MTA: dns; perso1.free.fr
X-Postfix-Queue-ID: 3705DD331F6
X-Postfix-Sender: rfc822; yyyyyyy@free.fr
Arrival-Date: Wed, 11 Nov 2009 21:19:42 +0100 (CET)

Final-Recipient: rfc822; xxxxxxx@aol.com
Original-Recipient: rfc822;xxxxxxx@aol.com
Action: failed
Status: 4.0.0
Remote-MTA: dns; mailin-01.mx.aol.com
Diagnostic-Code: smtp; 421-:  (RLY:CS4)
    http://postmaster.info.aol.com/errors/421rlycs4.html  421 SERVICE NOT
    AVAILABLE

Je peux faire quoi pour y remédier ?