More than 10 years ago, I needed a MIME decode for Windows as I was developing some software which implemented S/MIME could sign automatically generated emails and verify incoming ones.
I wrote more about the latter part in Some notes on OpenSSL, S/MIME, email, various RFC standards and their relations.
Now finally the post about what I wanted to schedule for posting back then as well: my question looking for a [Wayback/Archive] MIME decoder for Windows – Super User:
The Wiert Corner - irregular stream of stuff 