Share via

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

Koes 350 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?

Microsoft Exchange Online Management
Microsoft Exchange Online Management
Microsoft Exchange Online: A Microsoft email and calendaring hosted service.Management: The act or process of organizing, handling, directing or controlling something.
4,578 questions

165 answers

Sort by: Most helpful
Most helpful Newest Oldest
  1. Mehmet Yüce 20 Reputation points
    2023-10-11T11:44:34.96+00:00

    we have the problem in Turkiye

    4 people found this answer helpful.
  2. Cédric Blanchard 20 Reputation points
    2023-10-11T13:39:40.6133333+00:00

    Same here in Switzerland. Does anyone knows if there is a public dashboard from Microsoft to see the status of this issue ?

    4 people found this answer helpful.
  3. Ajay Rooplall 15 Reputation points
    2023-10-12T06:28:10.12+00:00

    Some users may encounter delays receiving external email messages in Exchange Online

    ID: EX680695

    Issue type: Incident

    Status

    Service Restored

    Impacted services

    Exchange Online

    Details

    Title: Some users may encounter delays sending and receiving external email messages in Exchange Online

    User impact: Users may have encountered delays sending and receiving external email messages in Exchange Online.

    More info: Impact was specific to Simple Mail Transfer Protocol (SMTP). Most users would have experienced up to a 1-hour delay; however, in some cases, users may have encountered delays of up to 24 hours. Additionally, the email sender may have received a Non-Delivery Report (NDR) with a "451 4.7.500 Server busy" error message, and their attempt to retry delivery of the email may have been delivered up to 24 hours later.

    Final status: We’ve completed our deployment of the change, which was a targeted reversion of the code issue causing impact. Users should now be experiencing mitigation, though some residual delays may still occur over the next hour as the change completes.

    Scope of impact: Impact was specific to some users who were served through the affected infrastructure. The issue affected users Worldwide and only for a portion of IP addresses, therefore not all users experienced impact.

    Start time: Monday, October 9, 2023, at 9:00 PM UTC

    End time: Wednesday, October 11, 2023, at 5:00 PM UTC

    Preliminary root cause: A recent service update that was applied to a section of infrastructure responsible for enforcing IP address anti-spam rules contained a code issue, which was resulting in the delays with SMTP email delivery.

    Next Steps:

    • We're further reviewing the recent update to understand how the code issue was introduced and to understand what prevented it from being detected in our update testing and validation procedures, which will allow us to prevent similar issues in future updates.

    We’ll publish a Post-Incident Report for this event within five business days.

    Are you experiencing this issue?

    3 people found this answer helpful.
  4. Hunter Rasco 5 Reputation points
    2023-10-11T13:39:07.0466667+00:00

    Has adding any of the IP addresses helped? Wanted to double check if this is the right spot to add to whitelist or not?

    1 person found this answer helpful.
    0 comments
  5. Hollósi Botond 0 Reputation points
    2023-10-11T12:23:13.19+00:00

    Hungary also affected.

    This outlook addressed are related:

    52.101.68.0

    52.101.68.3

    52.101.68.5

    52.101.73.1

    52.101.73.2

    52.101.73.4

    52.101.73.6

    52.101.73.8

    104.47.17.74

    104.47.18.74

    104.47.23.74

    104.47.30.10

    104.47.30.74

    52.101.42.10

    52.101.68.16

    52.101.68.18

    52.101.68.21

    52.101.68.32

    52.101.68.36

    52.101.73.11

    52.101.73.12

    52.101.73.15

    52.101.73.16

    52.101.73.19

    52.101.73.21

    52.101.73.22

    52.101.73.24

    52.101.73.26

    52.101.73.28

    52.101.73.30

    104.47.17.138

    104.47.23.138

    104.47.51.138

    104.47.51.202

    2023.10.11 14:23 CEST

Your answer

Answers can be marked as Accepted Answers by the question author, which helps users to know the answer solved the author's problem.