In order to view the questions in a timely fashion, I subscribe to some tags on SE, and created a label (subbox) in my Gmail named
stackoverflow. I receive lots of unread mails day after day and now I want to mark all mails under this label as read in a quick way, but I didn't see any options in the menu to do this.
The maximum items in a page is 100, if I do this page by page, I need to go through 50 pages to mark all the mails. It would be time-consuming.