Messages envoyés pris comme spam

Bonjour,
Lorsque j'envoie des messages avec outlook 2007, je reçois le message suivant:

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.

<nom@hotmail.com>: 550 SC-001 (BAY0-MC1-F5) Unfortunately, messages from 196.217.246.120 weren't sent. Please contact your Internet service provider since part of their network is on our block list. You can also refer your provider to https://sendersupport.olc.protection.outlook.com/pm/troubleshooting.aspx#errors.

ou bien le message suivant:

Certains des destinataires ou tous les destinataires n'ont pas reçu votre message.

Objet : RE: Demande de Collaboration 2013
Date : 17/01/2013 11:13

Impossible de contacter le(s) destinataire(s) suivant(s) :

'Sentier Berbere' le 17/01/2013 11:13
550 This message was classified as SPAM and may not be delivered

Merci de votre aide