[imp] smime

[Rick Emery]

Could someone point me to some good, easy to understand documentation about smime?

I have smime activated in imp. When I view a message that has been digitally
signed via smime, I get a warning at the top of the message view:

Warning: stat failed for /etc/httpd/conf/ssl.crt/ca-bundle.crt (errno=13 -
Permission denied) in /var/www/html/horde/lib/Crypt/smime.php on line 211

Within the message, I get:

This message has been digitally signed via S/MIME.

Message Verified Successfully but the signer's certificate could not be verified.

Now, I know that this is because there is something wrong with my setup, I just
don't know enough (anything) about smime to configure it correctly; hence the
request for pointers to documentation that even an idiot (me) can understand.

Thanks in advance,
Rick