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Microsoft - Advanced Threat Protection (ATP) Safe Links

In a continued effort to protect UMass Chan Medical School users, Information Technology has rolled out a feature within the University’s e-mail security system called Microsoft Advanced Threat Protection (ATP) Safe Links, replacing the previous Proofpoint URL Defense system.

How ATP Safe Links Works

ATP Safe Links scans incoming e-mail for known malicious hyperlinks and for attachments containing malware. This feature rewrites scanned URLs to Microsoft’s standard URL format prefix Once a link is rewritten, it is analyzed for any potential malicious content. If categorized as malicious you will be redirected to a block page upon accessing the link in your browser. ATP Safe Links works behind-the-scenes, which means you do not need to do anything to activate or take advantage of the system.

Screenshots of ATP Safe Links in Action

Rewritten URL’s can be observed by hovering over the link:

 Re-written URL in a ATP Safe Links E-Mail

The block page will look similar to this:

 ATP Safe Links Block Page

If you receive Plain-Text e-mails

When ATP Safe Links detects a hyperlink in a plain-text e-mail (non-HTML), it will rewrite the URL in plain text. In this case, you will see the rewritten URL directly in the body of the e-mail. E-mails with HTML or rich text are most common, so Plain-Text rewrites will occur infrequently.

If you forward an e-mail with a re-written link

Once ATP Safe Links has rewritten a URL, if the message is forwarded or replied to, the URL will remain rewritten. Additional links added to the message being replied to or forwarded will not be rewritten. If you believe recipients may have questions you could include the following in your signature:

“UMass Chan Medical School e-mail is protected by Microsoft’s ATP Safe Links product. Hyperlinks in this e-mail may begin with ‘’ and have a generally long format”

Additional Assistance

If you believe a URL has been blocked unnecessarily or believe a fraudulent site has not been blocked, please reach out to the Help Desk or email Information Security at

Rewritten ATP Safe Links URL to Original Link Converter

Please use the following text input to convert a rewritten ATP Safe Links URL to the original link.

Paste ATP Safe Links URL:

Decoded URL:

Click here to learn more about Office 365 Advanced Threat Protection.