[imp] Problem reading signed messages

[Veen, van Stephen]

Hello,

I'm running:

horde-2.2.3
imp-3.2.1
pear-1.1
php-4.2.2-17.2
httpd-2.0.40-21.9 (apache)

on a linux RedHat 9 system.

I have configured a POP3-server to contact and I have configured no LDAP or mySQL-backend (so options/userpreferences, memos, contacts, tasks are not available to users).

In /var/www/html/horde/imp/config/conf.php I changed:
$conf['mailbox']['show_attachments'] = false;
to:
$conf['mailbox']['show_attachments'] = true;

In /var/www/html/horde/config/mime_drivers.php I uncommented lines concerning several MIME-types. A list according the naming used in this config-file:

enscript
zip
msword
msexcel
mspowerpoint
rpm
deb

I have also configured:

$mime_drivers['horde']['text']['inline'] = true;

When I receive an unsigned e-mail with some plain bodytext and an attachment (content-type = multipart/mixed), I see a line that states the name of the attachment, its mime-type and an icon which I can click to download and view and below that the bodytext in plain text. This is what I want to see.
HOWEVER:
When I receive a signed e-mail (content-type = multipart/signed) with some plain bodytext and an attached signature (of type "application/x-pkcs7-signature") I only see a line that states an "unnamed" plain text document instead of the bodytext inline and the signature named "smime.p7s" as an attachment. Only after opening this document "unnamed" I can see the bodytext along with all the headers as well as the unreadable base 64 coded signature.
What I want to see is the body text inline and the signature stated as an attachment of type "application/x-pkcs7-signature" and named "smime.p7s" which I can click to download and view with some certificateviewer.

I added:
application/x-pkcs7-signature   p7s
to:
/var/www/html/horde/scripts/mime_mapping/mime.types

and I added:
'p7s'    => 'application/x-pkcs7-signature',
to:
/var/www/html/horde/config/mime_mapping.php

but this doesn't seem to help. What should I do to get what I want?

PS: I'm not intending to enable some ldap- or mySQL-backend, so please provide a solution that does not require a ldap- or mySQL-backend.

Thanks in advance for any help on this!

Kind regards,
Stephen van Veen
The Netherlands