Add an “Archive” button in KMail
I love the “archive” button in Thunderbird (which was adopted from GMail, I think…) and (so far) am enjoying KMail. However, I was missing the “read it, don’t need to do anything further with this email – so put it in my 2015 folder.”
A quick trip to the googles brought up a helpful post on Superuser.com that walks through the steps quite handily to set up a filter that you can apply manually. Probably obvious to folks who’ve been using KMail for a long time, but there ya go.