How to detect inline PGP in mails! Best practice?

[Sascha Kiefer]

Hi list,

i'm writing on a programm which verifies and decrypts messages as they 
arrive.
It it is fully S/MIME (using M$ Crypto API) and PGP/MIME (GnuPG) compatible.
The hardest problem i face is to detect inline PGP parts and handling 
them correctly:

* if the charset != us-ascii inside textmails is not always bad since 
most MTA's keep the
  original charset; so handling the data as binary is often the best 
choice!?!
* what about detached signatures of attachments?
* sending a PGP/MIME to this mailing list makes it even worse
  (see Topic: "GnuPG Clearsign vs. PGP/MIME Signing" for more details)
* ...

Do you have some hints?

Regards,
Sascha