macos tahoe 26 mail links won't open in safari

I have the same thing. not only in safari, but also in other browsers this is not working. So the issue lays inside the Apple Mail app. Cannot copy link and paste in to the browser either. Please fix this ASAP!

Same here. The links open (in any browser, doesn't matter which one) and the "nam12.safelinks.protection.outlook.com" safelink URL never unwraps and I get a 404 error. Even more interesting, I am unable to open the outlook webmail application at all (also in any browser). It results in the same 404 error message every time.