What does outlook.live.com mean in my referrers?

Why visits show an Outlook host

Outlook on the web is a website, and a click on a link in it works like a click on any other site. Unless a page asks for something else, browsers use the policy strict-origin-when-cross-origin, which sends only the origin (the scheme and host) to a different site. You get the host and nothing about the message.

Which host you see depends on the mailbox:

• outlook.live.com: a personal Outlook.com, Hotmail, Live or MSN mailbox.
• outlook.office.com and outlook.office365.com: a work or school mailbox on Microsoft 365.

The same mailbox read in the Outlook desktop program or a phone app reaches you under a different referrer or none.

Safe Links: when the link goes through Microsoft first

Microsoft can rewrite the links in an email so a click is checked before the visitor reaches you.

• For businesses with Microsoft Defender for Office 365, Microsoft says scanned links are wrapped with a prefix such as https://nam01.safelinks.protection.outlook.com, and a click is scanned before the user is sent on to the page. Admins can also switch rewriting off and check at click time instead.
• For Microsoft 365 Family and Personal subscribers with an Outlook.com, Hotmail, Live or MSN address, Microsoft says links may look longer and include safelinks.protection.outlook.com, and that this is on by default.

Microsoft doesn’t document what referrer your site receives after that hop. If safelinks.protection.outlook.com turns up in your referrers, treat it as an Outlook email click. Your tags survive the rewrite because they are part of the address being checked.

What it hides

It tells you the visit came from an email read in Outlook. It doesn’t tell you which email, who sent it or which link was clicked. A newsletter, a sales email and a forwarded message all look the same.

How to see which email it was

Tag every link you put in an email:

https://example.com/?utm_source=newsletter&utm_medium=email&utm_campaign=2026-09-update

Use a different utm_campaign for each send. The tags arrive whatever the mail app, the link check or the referrer does.

With Nordva Launch

Launch files outlook.live.com, outlook.office.com, outlook.office365.com and Safe Links addresses (safelinks.protection.outlook.com) under email. A link tagged with utm_medium=email counts as email whatever the referrer, and a tag naming another channel wins over the referrer too, which is one more reason to tag.