Setting Gmail as your default mail client

Chrome

This one is easiest. Open your Gmail account. At the right side of the address bar, you'll see two overlapping diamonds. Click those, and select "Use Gmail" or "Allow" (depending on your exact browser version).

Firefox

1. Click Firefox, Preferences.
2. Scroll down to Applications.
3. Look for "mailto" in the Content Type column. Next to it, click whatever is listed. It will turn into a drop-down list. Choose "Use Gmail".

Safari

There is currently no built-in way to do this in Safari. It's apparently possible with the Open In Webmail extension, but it requires a $0.99 purchase. I haven't tested this yet.

-- DavidBrodbeck - 16 Dec 2019