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Are You Facing the Frustrating Microsoft Link Blocking Issue?
A recent problem with a Microsoft service is causing trouble for people using Exchange Online and Microsoft Teams. Since early September 2025, many have found they cannot open links sent in emails or chats. This happens because Microsoft’s own anti-spam tool is making a mistake. It is wrongly identifying safe links as dangerous.
This issue not only blocks access to important web pages but also sends some emails to a quarantine folder, hiding them from users. Microsoft is aware of the situation and is actively working on a solution to restore normal service.
Understanding the Widespread Impact
This service disruption affects a broad range of users who rely on Microsoft 365 for their daily work. Exchange Online is the backbone of email communication for countless businesses, while Microsoft Teams is a central hub for collaboration, meetings, and file sharing. When links within these platforms stop working, productivity can slow down considerably. Imagine trying to access a shared document, join a video conference, or review an important invoice, only to find the link is blocked. This is the reality for many users affected by this glitch.
The problem creates confusion and concern. Users may worry that their computer or account has a virus. System administrators receive alerts about “potentially malicious URL clicks,” which adds to their workload as they must investigate these false alarms. The core of the problem is a false positive, where a security system overreacts and flags safe content as a threat.
Microsoft’s Official Acknowledgment
Microsoft has formally recognized the problem and assigned it the incident ID MO1148487. This code helps customers and technical support staff track the status of the issue. The company has shared details through its service health dashboard, providing updates to system administrators.
Here is a simple breakdown of the information Microsoft provided:
- Problem Title: Some users may be blocked from opening URLs in Exchange Online messages and Microsoft Teams.
- User Impact: People cannot open links. They may also find that some of their emails are incorrectly moved to quarantine. Administrators might also see false security alerts about malicious link clicks.
- Scope of Impact: The issue can affect any person who receives a message in email or Teams that contains certain types of URLs.
- Start Time: The problem began on Friday, September 5, 2025.
What Is Causing the Links to Block?
The root cause of this disruption is a specific error in one of Microsoft’s anti-spam filters. The system is designed to protect users from dangerous links, such as those used in phishing attacks. However, it is currently making a mistake with a particular kind of link structure.
The service is incorrectly flagging URLs that are embedded inside other URLs. This can happen for several legitimate reasons:
- Email Marketing Services: Companies often use services that wrap links in their emails. This allows them to track how many people click on the link. The original link is hidden inside a longer, tracking link.
- URL Shorteners: Services that shorten long web addresses can also create a URL that points to another URL.
- Safe Links Protection: Ironically, some security services, including Microsoft’s own, rewrite URLs to check them for threats before a user visits the site. This process itself involves wrapping the original URL.
The anti-spam filter is seeing this layered structure and mistakenly concluding that it is a malicious attempt to hide a dangerous website. It then blocks the link or quarantines the entire message to be safe, even though the final destination of the link is perfectly harmless.
Current Status and What You Can Do
Microsoft’s engineering teams are working to fix the problem. They have reported making progress and have resolved the issue for a majority of the affected links. However, they also identified a new set of URLs that were still being impacted and are continuing to work on a complete solution. The company is also investigating the root cause fully to prevent a similar incident from happening in the future.
While you wait for a permanent fix, here are a few things to keep in mind:
- Check Your Quarantine: If you are expecting an important email and it has not arrived, check your quarantine folder. Your administrator can help you with this. You may find the missing email there.
- Communicate with Senders: If a link you received is not working, you can try contacting the sender through another method. Ask them to send the link in plain text, without any formatting, which sometimes helps. For example, they can copy and paste the raw web address directly into the message.
- Stay Informed: Your organization’s IT department is the best source of information. They receive direct updates from Microsoft and can provide guidance specific to your company. They will know when the issue is fully resolved.
This incident highlights how complex and interconnected modern software services are. A small error in one component, even one designed for protection, can have significant effects on usability. Microsoft is focused on addressing the remaining impact and ensuring its systems can correctly tell the difference between a safe, wrapped URL and a genuinely malicious one.