[Bug 1290506] [NEW] KMail "Pipe Through" filter action breaks GnuPG signatures

[xor]

Public bug reported:

Used Ubuntu (lsb_release -a): Kubuntu 13.10
Architecture (uname -a): x86_64
Used kmail (dpkg --status): Version: 4:4.11.5-0ubuntu0.1                                                                                                                                         

Steps to reproduce:
- Generate a bogofilter spam filter using KMail's own wizard

- This will add a filter called "Bogofilter Check" which uses the "pipe
through" action to pipe the mail through "bogofilter -p -e"

- Now have someone send you a GnuPG signed mail which contains a text part which begins similar to this one (will try to upload an attachment which contains a whole sample message):
'--nextPart4479402.yrgGCOTjb2
Content-Type: Text/Plain;
  charset="iso-8859-15"
Content-Transfer-Encoding: 7bit'

- After the mail has been piped through the filter, the text part will be mangled to this:
'--nextPart4479402.yrgGCOTjb2
Content-Type: text/plain; charset="iso-8859-15"
Content-Transfer-Encoding: 7bit'

- As the header of the text part is part of the GnuPG signature, the
signature is broken now! There should not be ANY modifications on it for
GPG signature validation to succeed.

- If you pipe the same mail manually through "bogofilter -p -e" on the
terminal, and diff the before and after, you will notice that this does
NOT happen. This means that KMail is the one to blame for mangling the
header of the text part. In fact, it mangles a lot of more stuff about
the mail. Check the diff. IMHO, when doing "pipe through", KMail should
not do ANY modifications on the mail at all.

** Affects: kdepim (Ubuntu)
     Importance: Undecided
         Status: New

-- 
You received this bug notification because you are a member of Kubuntu
Bugs, which is subscribed to kdepim in Ubuntu.
https://bugs.launchpad.net/bugs/1290506

Title:
  KMail "Pipe Through" filter action breaks GnuPG signatures

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/kdepim/+bug/1290506/+subscriptions