Open the mailing list permalink of the (popular webmail client) message you're looking at.
When you're in geeeemail sometimes its nice to get a permalink of the message you're looking at. This extension will help you out with that for a few mailing lists:
1) google groups
2) google groups for your domain
3) w3.org mailing lists
4) webkit-dev
5) whatwg
Just click the Show Original link on the message and the extension will take over from there.
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Fork it: https://github.com/paulirish/Gmail-mailing-list-permalink-chromeext