How to tell everyone on Gmail if you’re in — or not

Recently, a friend who has been on Gmail for a long time suddenly noticed the chat availability settings in the upper right of the web app. This notice was actually added to the Gmail page about two years ago when Google Chat was integrated into Gmail. It notifies anyone whom you’ve ever used Chat with that you’re at your computer (or phone) and available — or not.

Even though most people may not receive notification of your…