When you click on a linked email address (like this one, try it: firstname.lastname@example.org), your computer has a default application that will open the link. Maybe it's Microsoft Mail or Microsoft Outlook or Apple Mail. But what if you just want the link to open in Google Mail instead? If you clicked that link above and a new Google Mail tab DID NOT open, this article is for you.
How to Set Gmail as the Chrome Default for Mail Links
If you use the Chrome browser, here's how you can make all links (like the one above) open a new Google Mail window.
1. Navigate to mail.google.com. Log in with your TSS credentials, then wait for the page to load.
2. Once the page loads, look for a small icon in the OmniBox (search bar) that looks like two overlapping diamonds. Click on the icon, then choose "Allow", then click Done.
3. That's it! Try it now by holding down the CTRL key and clicking this link: email@example.com. If a new Google Mail tab opens up with a Compose window, you're done.
But Wait, I Don't Use Google Chrome!
If you use a different web browser, the procedure is a bit different. This article gives a good rundown of your options: http://www.makeuseof.com/tag/how-to-change-the-default-email-program-for-mailto-links/