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i have personally realized that relevance is not always good while looking for a recent email.
Say you want to pull up information for your upcoming trip, so you search for the keyword “flight itinerary.” Historically, your search results page would sort searches by date, requiring you to scroll through many promotional emails from airlines before finding the right one. Now, you will see up to three most relevant emails at the top of your search results, making finding the info you need that much quicker and easier. And have no fear, all other relevant search results will still be available beneath “Top Results” ordered by date.
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