Introduction
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How do “Safe Links” work?
Microsoft’s Safe Links service 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 https://nam01.safelinks.protection.outlook.com. Once you click a rewritten link, Microsoft analyzes the link for potentially malicious content. If a link is categorized as malicious you will be redirected to a web page that blocks you from reaching the intended link. Safe Links works behind-the-scenes in Outlook on your PC or on web-based Outlook – you do not need to do anything to take advantage of this service.
Example URL with and without Safe Links enabled:
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How does this impact you?
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However, if the link is scanned and found to be malicious, you will be presented with this warning:
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If you receive Plain-Text e-mails
When 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 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.