How to control the email file name procmail produces

Hi list,

I'm using fetchmail and procmail to do my emails fetching and
processing.

I let procmail process the emails from fetchmail and divides them into
dirs(maildir), I find the file name is something like:

    1286938757.42024_0.fbsd.t60.cpu:2,S

it works fine in *nix. But someday when I want to move the dirs onto a
fat32 filesystem, I failed and I found the reason is that the files
name has some inlegal characters, maybe : or ,?

So my question is, how to let procmail produces files without some
charactors?

-- 
Regards,
Yue Wu

Key Laboratory of Modern Chinese Medicines
Department of Traditional Chinese Medicine
China Pharmaceutical University
No.24, Tongjia Xiang Street, Nanjing 210009, China