If clicking on a mailto link brings up a Google webpage, you clicked "yes" when chrome browser asked you whether you wanted to launch Gmail when you click on a mailto link.
- Click this mailto link to test > Does Outlook open?
If Outlook does not open, follow this Win 10 guide to quickly fix
Search and click 'Default app settings' and select Outlook:
If Outlook does not open, follow this Win 8 guide to quickly fix
Sort 'Current Default' column and find MAILTO:
Click 'Change program...' and select Outlook:
Now Outlook will open mailto links as it used to before installing Chrome browser.