Arreglar rechazo de correos por parte de Hotmail

Tengo mi servidor de correos en un hosting privado y Hotmail rechaza los correos de todos mis clientes con el siguiente mensaje:

<########@hotmail.com>: host
    hotmail-com.olc.protection.outlook.com[104.47.14.33] said: 550 5.7.1
    Unfortunately, messages from [198.71.XX.XXX] weren't sent. Please contact
    your Internet service provider since part of their network is on our block
    list (S3140). You can also refer your provider to
    http://mail.live.com/mail/troubleshooting.aspx#errors.

    [Vi1eur04ft040.eop-eur04.prod.protection.outlook.com] (in reply to mail
    from command)

ya intenté desbloquearlo desde su página pero su respuesta ha sido la siguiente:

we have completed reviewing the ip(s) you submitted. The following table contains the results of our investigation.


Not qualified for mitigation
198.71.XX.XXX
Our investigation has determined that the above IP(s) do not qualify for mitigation.

Please ensure your emails comply with the Outlook.com policies, practices and guidelines found here: http://mail.live.com/mail/policies.aspx.

To have Deliverability Support investigate further, please reply to this email with a detailed description of the problem you are having, including specific error messages, and an agent will contact you.


Para poder pagar el trabajo requiero que se puedan recibir los correos en hotmail desde las diferentes cuentas de mis clientes.