Version:           1.6.1 (using KDE 3.2 BRANCH >= 20040204, Mandrake Linux Cooker i586 - Cooker)
Compiler:          gcc version 3.3.2 (Mandrake Linux 10.0 3.3.2-6mdk)
OS:                Linux (i686) release 2.6.3-14mdk

Loaded plugin (initialised, no matter if
active or inactive):
/usr/lib/cryptplug/gpgme-smime.so

Cannot create a backtrace (manually removed the mail that made kmail crash from inbox).

I can send you the complete text of the mail that caused the crash, if you want to have a look at it.

The crash was reproducible: it occurred every time I clicked on the (newly received) mail in the message list. When trying to 
decode the mail, kmail crashed.
The crash happened also for a second (different) mail I received from the same person. The mail (from Outlook/Office 2003) contains a S/MIME signature, which is added as an attachment.

Here is a part of the mail header:
-----------------------------------------
Subject: RE: Exchange
Date: Thu, 1 Jul 2004 10:47:20 +0200
MIME-Version: 1.0
X-Mailer: Microsoft Office Outlook, Build 11.0.5510
Content-Type: multipart/signed;
  protocol="application/x-pkcs7-signature";
  micalg=SHA1;
  boundary="----=_NextPart_000_0064_01C45F58.C809C220"
Thread-Index: AcRfNrZJj5dmIzy6TxmfXZhJdUXtKAADpQ4gAACVX6A=
In-Reply-To: <200407010830.i618U8Hp023256@pilz.exp-math.uni-essen.de>
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1409
X-UIDL: D>f"!2b9"!#[=!!aEp"!
X-Spam-Checker-Version: SpamAssassin 
-------------------------------------------

The signature was added as attachment, like this:

------=_NextPart_000_0064_01C45F58.C809C220
Content-Type: application/x-pkcs7-signature;
        name="smime.p7s"
Content-Transfer-Encoding: base64
Content-Disposition: attachment;
        filename="smime.p7s"

MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCG
...etc. etc. etc. and more....

Expected Behaviour:
KMail should have displayed message text, and signature (either as a signed message,
or as attachment of the signature type application/x-pkcs7-signature.