To import a new CA certificate into Thunderbird 1.5:

1. Launch Thunderbird and choose Account Settings from the Edit menu.
2. Select Security under the account name.
3. Click the View Certificates button.
4. Click the Authorities tab.
5. Click the Import button at the bottom of the screen.
6. Navigate to the CA certificate and import it.

To import a new CA certificate into Evolution:

1. Launch Evolution and choose Preferences from the Edit menu.
2. Select Certificates
   

With centralized email control, it is recommended not blindly dropping and/or quarantining affected messages, but rather politely adding a header that the informed user client can check later. This has the bonus of increasing user awareness, providing the user with a tool he or she can easily use for sorting emails and not giving administrators the troublesome problem of dealingwith quarantined messages.

Sending PDF files in email used to be a safer way to transmit documents a couple of years ago. Not anymore. We are seeing more and more PDF files containing virus that manage to slip through the antivirus scanning and damage users computer. In fact, PDF files and QuickTime movies are getting exploited a lot these days for spreading viruses around.

My solution to virus and malware fighting:

Use a dedicated computer for email communication and browsing unknown websites. Then use another computer(s) for your daily regular work.