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Outlook-TUmail Outbound Email Delivery

Microsoft has alerted us of instances where outbound TUmail emails were being marked as spam and not delivered. This has been seen with third-party email systems such as Yahoo, GMail, Verizon, and AOL. Microsoft is working with a third-party anti-spam service to determine the Microsoft email IP address ranges that are problematic to resolve the issue.   

Per Microsoft and this update, "We've seen drastic improvements and significant reduction in the volume of impacted messages due to our implemented optimizations. We continue to proactively identify and stop spam messages through our ML antispam systems, as well as respond and implement further adjustments manually to block messages we manually find. Given that our optimizations have been successful, and because there's no means to prevent all spam messages from ever occurring, we're declaring this event resolved". 

Root cause: A third-party anti-spam service was blocking a portion of Microsoft’s email IP address ranges to protect organizations that used their services.

Start time: Tuesday, January 2, 2024, 12:00 AM UTC
End time: Wednesday, April 24, 2024, at 10:30 PM UTC

Next steps:
- We're further working alongside the third-party anti-spam service to determine a proactive measure to identify Microsoft's email IP address that are causing future impact and to implement optimizations before impact reoccurs on a broader scale.

This is the final update for the event.

We appreciate your patience for those that have encountered this issue.

Last Update At: Wednesday, Apr 24, 2024 08:16 PM