openssl x509 -inform DER -outform PEM -in /tmp/IN-Berlin-G3-root-certificate.htm  -out /tmp/IN-Berlin-G3-root-certificate.pem

This works on a Debian Etch sytem

cp /tmp/IN-Berlin-G3-root-certificate.pem /etc/ssl/certs/
c_rehash

• http://support.citrix.com/article/CTX106631
• man fetchmail