So, we have problem with attachments names because rfc2231 is not (fully) supported in Outlook (and some other clients). Maybe we should consided to do something with that before 0.2-beta release? Here's discussion how it's done in Thunderbird. In short: Thunderbird encodes filename value with rfc2231, but name value with RFC2047 (quoted-printable). That may be a good solution also for as.
lost link https://bugzilla.mozilla.org/show_bug.cgi?id=309566