Have a look in 'View' and make sure you have got 'Show all Messages' ticked and not 'Hide Read Messages'
That varies slightly depending on which email client you are using so it is whichever toolbar menu takes you to that setting.
OnePlus 5T review: Hands-on
Illustrator Andrés Lozano on his improv line work, brazen use of colours & hand sketching
iPhone X review
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