Extract e-mail attachments on Unix
mpack did it for me! (actually the munpack part) Exactly what I needed: tiny standalone executable with no extra.
Another solution is to use uudeview. Works similar to munpack. Just type
$ uudeview file.eml
A very long time ago, I used metamail for exactly this sort of thing.
see https://kb.iu.edu/d/aibt
M.