It’s IP specific, and is dynamically assigned. Aloha, Michael. -- Michael J Wise Microsoft Corporation| Spam Analysis "Your Spam Specimen Has Been Processed." Open a ticket for Hotmail<http://go.microsoft.com/fwlink/?LinkID=614866> ?
From: Matthew Pounsett <[email protected]> Sent: Friday, February 20, 2026 2:50 PM To: Michael Wise <[email protected]> Cc: [email protected] Subject: Re: [EXTERNAL] [mailop] Anyone from Outlook? S3150 block list mirage On Fri, Feb 20, 2026 at 5:01 PM Michael Wise <[email protected]<mailto:[email protected]>> wrote: It’s throttling. Slow down your deliveries. The rate limit must be incredibly low, if that's the case. We sent less than 1500 messages to outlook.com<http://outlook.com/> mail servers all day on February 20th. If it is a rate limit, then please share where the rate limit is documented, so that I can set the throttle appropriately. I can't keep under a rate limit if I don't know what it is. And if it's a rate limit, why are we getting 500 errors instead of 400? That should be a temporary error.
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