We have not received reports of further issues with Microsoft freemail services (msn / live / hotmail / outlook.com) services. We believe whatever caching / DNS problem was associated with the IP address range has been resolved. Note from the NOC:
Microsoft relies on Smart Network Data Service and ExchangeDefender has all our ranges registered with the abuse service so we're notified in realtime of any complaints of SPAM or malware originating from our client base. ExchangeDefender never received any complaints from SNDS and our IP address was erroniously listed in an RBL that Microsoft relies on. Even though the listing was removed and Microsoft / SNDS never identified any issues, our assessment is that the RBL lookup may have been cached.
In the meantime, we have redesigned our routing topology to spit Microsoft freemail services from Microsoft M365/Entra business services and other significant improvements in routing IP to minimize the impact of this type of an event in the future.
Update 08/03/2026 21:03 PM 21 days
We are still working with Microsoft SNDS which is in charge of issues with msn.com / live.com / hotmail.com freemail.
In the meantime, our mail has been re-routed as we continue to work on this. Delivery should not be impacted at this point. We will advise when routing returns to normal.
Update 07/29/2026 19:55 PM 26 days
Bounce message sample:
From: Mail Delivery Subsystem <MAILER-DAEMON@outbound1.exchangedefender.com>
Sent: Tuesday, July 28, 2026 1:17 PM
To: xxxxxx@msn.com <xxxxxx@msn.com>
Subject: xxxxxxx
----- The following addresses had permanent fatal errors -----
<xxxxxxxx@msn.com>
(reason: 550 5.7.1 Unfortunately, messages from [207.210.228.195] weren't sent. Please contact your Internet ...DD0E557A63D1E] [BL6PEPF0001AB4E.namprd04.prod.outlook.com 08DEE872B1014535])
----- Transcript of session follows -----
... while talking to msn-com.olc.protection.outlook.com.:
>>> MAIL From:<xxxxxx> SIZE=3621867
<<< 550 5.7.1 Unfortunately, messages from [207.210.228.195] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [Name=Protocol Filter Agent][AGT=PFA]
554 5.0.0 Service unavailable
Update 07/29/2026 19:52 PM 26 days
We have received reports of ExchangeDefender IP addresses listed on Microsoft's freemail services.
We have raised an issue with Microsoft SNDS and we are awaiting delisting. In the meantime, IP addresses have been removed from outbound rotation so any RBL rejections but some rejections are still coming in as if cached. We have not received any reports of abuse nor are we able to escalate the issue.
In the meantime, and if you urgently need to deliver mail from your email address to msn.com or live.com, you can rely on our bypass.exchangedefender.com service that its included with your license. Just login to admin as usual, click on Bypass and then send email bypassing the ExchangeDefender network entirely.