Migrating emails from Notes to Outlook (or, programming for failure)

My huge archive of Lotus Notes emails started almost ten years back, and I stubbornly kept most of it around because of why not. Now that I use Outlook 2013 you can imagine I would have liked to have all of them also in my brand new email client. One sure could get some commercial software to do it, but why shouldn’t I try converting them myself? I mean, look, a simple drag and drop from Notes creates in Windows Explorer EML files and we all know EML is a very much standard format (RFC822 or so). Or at least that’s what I thought – Outlook 2013 thinks differently and will not import EML files. Only Outlook Express or Microsoft Live Mail can do that, but who cares about these anyway?? So what are my options?