If you're a productivity nerd like me you've probably tinkered with some of the highly useful stuff tucked away in the opt-in corner of Gmail Labs, and if you travel frequently or tend to keep tabs on or work with folks globally you might appreciate this one. Today the web-based email client gets the "Sender time zone" feature, which helps you more easily keep track of which time zone a received email was sent from and estimates whether or not the sender is likely to be online and working or out of the office.

Once enabled under the Labs settings (it's a little green chemistry beaker icon in the upper right if you haven't played with Labs yet) the feature will display a green phone icon next the sender's name if it's between 9 am and 6 pm in their timezone; if not, the icon is red. You can expand the "show details" headers of any message to see what time the message was sent in their timezone and what the current time is there now. The gist of the feature is to give you a quick heuristic to tell at a glance who is probably awake and therefore likelier to respond to any return message quicker, or likely asleep or not working so as not to expect a quick reply.

The sender time zone guestimates certainly break down in a number of cases — not everyone works 9 to 6 in their own timezones, and frequent travellers might not even be in the same timezone they sent the message from by the time you see it. Still, it's a quick and dirty little value add that's one of the Gmail Labs goodies worth enabling to see if you find it useful (I'm also a big fan of Tasks, multiple inboxes, and the Google calendar and docs gadgets). We'll be keeping it on for a while as a handy way to remind us of east vs. west coast colleagues; if you try it out let us know your thoughts in the comments.

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