outlook.com servers tells "Server busy. Please try again later from"

Question

Sice today morning we have many e-mails on outgoing queue, where is similar part:

....eu.mail.eo.outlook.com[52.101.68.0] said: 451 4.7.500 Server busy. Please try again later ....

I mentioned, that this seems to be global problem as in forums are discussed about this also.

If this is somehow related with certain sender IP-addresses, then where is the place, where I can report, that my IP-s can be released from blacklist, if they are there at all.

Actually tag "Exchange online management" was put only, that something needed to enter there.

Answer 1

Known issue:

Title: Some users may encounter delays receiving external email messages in Exchange Online User impact: Users may encounter delays receiving external email messages in Exchange Online. More info: Affected users may see a "451 4.7.500 Server busy" error message. Current status: We’ve identified that a recent service update, applied to a section of infrastructure responsible for enforcing IP address anti-spam rules, contains a change which is inadvertently causing impact. We’re developing and validating a fix to revert to the most recent stable service version to remediate impact. In parallel, we’re continuing to manually add reported affected IP addresses to an allowed list to alleviate impact in the short term. Scope of impact: Impact is specific to some users who are served through the affected infrastructure. Start time: Monday, October 9, 2023 at 5:00 PM EDT Root cause: A recent service update, applied to a section of infrastructure responsible for enforcing IP address anti-spam rules, contains a change which is inadvertently causing impact. Next update by: Wednesday, October 11, 2023 at 10:30 AM EDT