Making links safer in Outlook

Introduction

Perhaps the fastest way to compromise a user’s computer and steal data is to get the user to click on a malicious Internet link in an email. That’s why we provide periodic training to Franklin County users to defend against that threat. But we also use technical countermeasures like the Safe Links service from Microsoft, which examines the links sent to you in email and prevents you from clicking over to malicious websites or other destinations.

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:

How does this impact you?

With Safe Links turned on, you may notice hyperlinks in received emails will contain a (much) longer URL when they hover a link. For example:

Clicking the link first takes you to https://na01.safelinks.protection.outlook.com but then immediately redirects you to the original URL – but only IF the URL has been scanned and determined to be safe.

However, if the link is scanned and found to be malicious, you will be presented with this warning:

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.

Page Contents

1 Introduction
2 How do “Safe Links” work?
3 How does this impact you?
4 If you receive Plain-Text e-mails
5 If you forward an e-mail with a re-written link

FCDC User KB