How do I remove a digital signature from a msg file?

[JoMill]

Hi,

we have signed, encrypted and signed+encrypted msg-files and PST-
entries. We want to convert them in "regular" msg-files, i.e. the
usual MAPI properties and no p7m attachments. We managed to decrypt
the encrypted ones (CryptoAPI, IConverterSession::MIMEtoMAPI). But the
signed ones still contain their body, attachments, etc. in the p7m
attachment. It's not encrypted but we don't want to write a p7m parser
when not absolutely necessary.

So here's my question: Is there a way to convert a signed email with
p7m attachment into an unsigned email without p7m attachment?

Thanks,
JoMill