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.

Related Posts

Microsoft and SPF

Many deliverability folks stopped recommending publishing SPF records for the 5322.from address to get delivery to Microsoft. I even remember Microsoft saying they were stopping doing SenderID style checking. A discussion on the emailgeeks slack channel has me rethinking that.

Read More

SenderID is dead

A question came up on the email geeks slack channel (Join Here) about SenderID. They recently had a customer ask for SenderID authentication.

Read More

How accurate are reports?

One of the big topics of discussion in various deliverability circles is the problems many places are seeing with delivery to Microsoft properties. One of the challenges is that Microsoft seems to be happy with how their filters are working, while senders are seeing vastly different data. I started thinking about reporting, how we generate reports and how do we know the reports are correct.

Read More