Change Gmail Time Interval Settings For Marking Emails As Read In Preview Pane

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If preview pane is enabled in Gmail, the default interval for marking the mails as read once they are visible in preview pane is 3 seconds. (To enable preview pane, simply click on the toggle split icon at top right of Gmail inbox and choose a vertical split, horizontal split or none). Now for changing this interval of marking emails as read in preview pane, go to Settings by clicking on gear...