In order to view the question timely, I subscribe some tags on SE, and create a label(subbox) in my gmail named as stackoverflow.

I got lots of unread mails day after day. now I want to mark all mails under this label as read with a quick way, but I didn't see any options in the menu can 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. this is time-consuming.

any idea?