It seems like the mailto links we\'re embedding in our website fail to do anything in Chrome, though they work in Firefox.
Simple example here: http://j
On macOS check also the Mail.app settings, which App is selected as default email App / associated with mailto: links:
If you ever clicked that notification on Gmail, which allows to open links in Gmail instead your App - and after this reset the Chrome handler, you have to edit this manually in your Mail.app Settings.