One of my favorite Gmail Labs feature is “Sender time zone”. This feature adds a tiny red or green icon (the color depends on the sender’s local time) to all incoming emails. This will help you to determine whether local time for the sender falls inside or outside of the workday.
To turn on this feature, you’ll need to use the settings menu within Gmail and then navigate to the Labs tab.
Turn on the sender time zone feature and let Gmail restart.
Once you enable this feature, each email that lands in your inbox has either a red icon or a green icon depending on whether the sender’s time is between 9am and 6pm (green) or outside those hours (red).
Unfortunately, there’s no way to set the working hours as per your choice. You will have to go with the regular 9am to 6pm rules for determining whether the icon is red or green.
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