E-Mail sending to Offcie/Microsoft365 customers not possible - 451 4.7.500 Server busy

Koes 360 Reputation points
2023-10-11T10:38:11.0866667+00:00

Hi,

since this morning 5 am we are not able to send E-mails to office365/Microsoft365 Customers. Our Mails are stuck in our own queue and get the response: host customername.mail.protection.outlook.com 451 4.7.500 Server busy please try again later wit 193.228.149.133 S77719

Can someone check, why we are on an throtteling list with our E-MailServer and remove please?

Exchange Online
Exchange Online

A cloud-based service included in Microsoft 365, delivering scalable messaging and collaboration features with simplified management and automatic updates.


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  1. Jakub Matas 0 Reputation points
    2023-10-12T06:30:08.1533333+00:00

    @outlook.com , please allow these two affected IPs to your whitelist:

    46.36.35.104
    46.36.39.26
    46.36.35.9
    46.36.41.181

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  2. Kaňa Mikuláš 0 Reputation points
    2023-10-12T06:40:33.15+00:00

    @outlook.com , please allow these IPs to your whitelist:

    77.78.100.193

    217.11.227.76

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  3. NOC 0 Reputation points
    2023-10-12T07:08:44.17+00:00

    seems solved, thx

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  4. Murat varici 0 Reputation points
    2023-10-12T07:39:17.17+00:00

    Türkiye

    @outlook.com , please White List the following IP:

    88.233.195.190

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  5. natan jamal 0 Reputation points
    2023-10-12T07:47:45.8966667+00:00

    @outlook.com Please add to whitelist - country Poland

    86.111.240.3/32

    86.111.240.247/32

    86.111.240.234/32

    86.111.240.243/32

    86.111.240.252/32

    86.111.242.220/32

    86.111.242.222/32

    86.111.242.224/32

    86.111.242.225/32

    86.111.242.228/32

    86.111.241.108/32

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