It’s easy to end up with vast numbers of Gmail messages marked unread even when they’re not. For instance, if you’ve imported hundreds of messages from another account. To avoid having to do this manually page-by-page here’s the easy fix:
- Go to Settings (click on the gear wheel icon at top right of your screen).
- Select “Mail Settings”.
- Select the “Filters” tab.
- Click on “Create a new filter”.
- In the box labelled “Has the words:” enter is:unread.
- Click on the “Next step” button.
- Click the OK button on the warning screen.
- Check the “Mark as read” box and the “Also apply filter to x conversations below..” box.
- Click the “Create filter” button.
Delete the filter when you’ve finished.