How to mark all your emails as read in Gmail

You can mark all emails in your inbox as read on the desktop version of Gmail, or you can limit it to emails within a folder, like promotions.
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Gmail, Mail and "mark all messages as read"

An annoying quirk of either gmail or Mail is that gmail inboxes don't seem to stay synchronized and the folders have the annoying numeric-bubble indicating unread emails. I constantly have to manually ...

How to delete all your emails on Gmail, or mass-delete a specific amount of emails at once

To mass-delete all your emails on Gmail, click the "Select" box, then "Select all conversations." Or you can choose specific ...