Using Message-ID as unique file name?

Is it safe(possible) to use  Message-ID as unique file name
for later reference?
Or does it incur problems due to meta characters which might be
included in ID?

If it is not safe, 
is there any way I could refer(know) the unique file name
just created automatically by directing email to directory textmail/.
in same recipe?

Or is there any easy way to create unique file name
and refer it in same recipe?

_/_/_/      Mitsuru FURUKAWA      _/_/_/
_/_/_/        Tokyo, Japan        _/_/_/
_/_/_/     mailto:furu(_at_)009(_dot_)com    _/_/_/
_/_/_/  http://www.009.com/furu/  _/_/_/