When click Mailto links online, Chrome and Safari default to Microsoft Outlook Online. I don't have Outlook. How do i change it?

Hi, thanks, had tried that, but it doesn't work if Outlook webmail hijacks your browser settings/ blocks other clients in mail handling services, as i found out was the case after more research. It actually put my clients as Blocked for mail handling in the browser settings, and it did it without my son being aware of it. He probably mindlessly clicked some alert allowing Outlook to become the default handler.

Therefore, trying to change the default to my own email accounts (gmail, icloud) didn't work, because their default client(s) had been blocked from being used as handlers, and Outlook had set itself as default, and turned off setting for sites to ask.

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If someone else runs into this, here is the updated instructions to undo this in Chrome (in this example, gmail handler desired). I haven't figured out how to undo it in Safari yet.

1. Open Chrome Browser and click More Settings.
2. Go to the Privacy and security section.
3. Next to Site Settings, click the Right arrow 
4. Scroll down to Additional permissions and click Expand .
5. Next to Handlers, click the Right arrow .
6. At the top, make sure Allow sites to ask to become default handlers for protocols (recommended) is turned on.
7. Note: Scroll down to the Blocked section and make sure that mail.google.com doesn't appear in this list.
8. In your Chrome Browser's address bar, enter mail.google.com.
9. Click Service handler .
10. Click AllowDone.

thanks. There were no added extensions in safari, and I didn't do anything additional (i had deleted caches, restarted, etc), but it is now working since i fixed the issue in Chrome. Gmail my default mailto in System prefs, perhaps Mailto's were somehow defaulting back to Chrome even from Safari and getting rejected because gmail was blocked....?! Dunno, but it's working now... thanks all. This was a weird one, hope this info helps anyone else this happens to.