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The Microsoft Outlook Network Still Rejects Emails Sent From Linode Servers

Microsoft looks to have given Linode IP addresses the unwelcome Christmas present of email blocklisting, and the corporation does not appear to be willing to back down two weeks into 2022.

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Linode is an infrastructure-as-a-service company with data centers all over the globe. As an alternative to the big players, one can host apps, including email services and data on their platform. Well, that’s until Microsoft decides to add the IP addresses from which one is transferring data to a blocklist.

As broad swaths of the globe began packing for the holidays, problems arose. Customers began reporting difficulty sending emails to Microsoft 365 accounts from their email servers, which prompted complaints on Linode’s help forums.

On that discussion, a Linode employee acknowledged the problem and suggested a few third-party email services as a workaround, and had the following to say:

“Microsoft has acknowledged the problem and is looking into it.”

More recently, the Linode team has offered to swap out afflicted IPv4 addresses for unaffected ones – or, for a price, to provide new ones to users who are experiencing issues.

Linode had the following to say:

“While we cannot control how long it takes for Microsoft to address the issues on their end, we do have potential solutions that we can offer to help customers avoid the current ‘Banned Sender’ bounces.”

Users were also asking about forbidden sender bounces for emails from Linode IP addresses on Microsoft’s forums.

One User had the following to say:

“Most of our clients but not all hosted with Microsoft don’t get our emails because of this issue.”

Blocklisting IP addresses to prevent the delivery of spam emails is a simple notion. Still, Microsoft has been more passionate about it over the years than is necessary. tsoHost’s bulk email domain was placed on the naughty step for Outlook and Hotmail addresses in 2019, and getting it off proved difficult.


David Bennett, who is a Register Reader, had the following to say:

“Requesting to delist via their automated portal doesn’t work as it claims the IPs aren’t blocked. I personally have half a dozen servers with them, and the only way I’m managing to get any progress is opening tickets as I’m also a 365 customer and requesting escalation until I finally find someone who has access to the super-secret list. It’s a really big problem for tons of businesses, charities, etc., given how many folk use 365 for their email and how many sites rely on being able to send emails to them!”

It demonstrates how many people have delegated the burden of managing their email to Microsoft recently. Everything is okay until anything is added to the blocklist and can no longer be scratched off.

The problem appears to be improving in recent days, as some Linode users have reported that some IP addresses have been released after begging, appealing, and escalating (like our reader). Others, on the other hand, are steadfastly outside in the cold.

A Linode Spokesman, had the following to say:

“Currently, the number one priority for our Trust and Safety team is this issue. We’re iterating on changes we think are going to help address this and have been working with Microsoft to identify the issue and get it solved as quickly as possible. Our community team will update the thread as soon as there is a resolution.”