First click on the "Labels" drop down box, select "Create new" and create a label called something like "AOH"
In very small print, just to the right of the search box, there is a link "Create a filter", click on this and then paste the name of the listserve, in this case "firstname.lastname@example.org" into the "To:" box. Click next.
In the next screen, tick the box to the left of "Skip the Inbox" and then go to the "Apply label" drop down box and select "AOH" or whatever the label was you set up in step 1).
If you like, tick "Apply to existing conversations" then click"Create filter"and that's it.