Mac Mail: How to have mail popups show for only a couple seconds Whenever I get mails from Mail on my mac, they just stays there until I have to manually close the notification. Is there anyway to make the popups automatically go away after 1-2 seconds? 

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As mentioned you can change the Notifications settings in Notification Center. 

You have the Mail alert style set to alert which makes the notification stay until dismissed. 

To make the notification disappear after a few seconds you need to change the style to banners in Notification Center.

Shown below: