I won’t rehash all the details Microsoft have above, but Safe Links give a time of click assessment of a URL to check if they deem it safe. This can be better than time of delivery of the URL, as new threats emerge or the end results of the URL change.
To enable Safe Links for Teams, go to the Safe Links Policies & rules section of Microsoft 365 Defender https://security.microsoft.com/safelinksv2
From here, you probably just have one policy but could have more – edit the policy to affect the users you want, and in the “Protection settings” area, there will be an “Edit protection settings” link
Once editing, just set the radio button to ‘on’ against ‘Select the action for unknown or potentially malicious URLs within Microsoft Teams. Microsoft haven’t updated the warning around being in preview despite the GA announcement.
Once done, and waiting for a timeframe I’m not sure on, Teams will start using Safe Links. URLs being used in Teams look the same as before, and even if you hover over them, they show the actual end result link:
But when clicked, you’ll see this jump page while Microsoft Defender for Office 365 verifies the link:
Regardless of the link being clicked, the URL for me always displayed this:
It verified the link very quickly in my testing, less than a second each time. At this stage I can’t see any way to configure this page, or disable the option to Skip verification to enforce security, but we’ll see what happens.