Deferrals at Microsoft

If you’re seeing a lot of “451 4.7.500 Server busy. Please try again later” from Office365 this morning you’re not alone.

Microsoft are aware of the issue, and incident EX680695 says:

Current status: We’ve identified that specific IP addresses are being unexpectedly limited by our anti-spam procedures, causing inbound external email delivery to become throttled and delayed. We’re reviewing if there have been any recent changes to our anti-spam rules to understand why the IP addresses are being limited. In the meantime, we’re manually adding reported affected IP addresses to an allowed list to provide immediate relief.

When Asking a Question
Wildcards and DKIM and DMARC, oh my!

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