Open Chrome, and then go to https://mail.google.com
In the right end of the address bar, click the Service Handler icon
Click Allow, and then Done.
If this icon does not appear in the address bar, follow these steps:
- Close any open Gmail tabs in chrome.
- Type chrome://settings/handlers into your address bar and press enter.
- Remove any entries listed under email by clicking button and selecting Remove
- Under Default Behavior, make sure Sites can ask to handle protocols is selected
- Close the settings tab.
- Open https://mail.google.com in a new tab. You should now see the Service Handler icon at the right of the address bar.
- Click the Service Handler icon, then select Allow and click on Done.
If this does not work, try returning to the handlers settings screen, click the triple dot menu next to the Gmail entry and select "Set as default"
Additionally, as a work around, two-finger click on the Email Parents link, and then choose "copy email address". Paste this into a new compose window in Gmail.