If using Microsoft Internet Explorer 6 or earlier, click on the file and choose Open to import the certificate or revocation list, be sure the CA certificate is installed under Trusted Certificate Authorities. For Internet Explorer 7, you'll need to save the file to your desktop, then double-click and choose Open, then click Install Certificate.
Firefox/Mozilla browsers only support binary DER certificate revocation lists, thus, this is available in addition to the standard PEM base64 endocded certificate. Users should see a prompt to accept and import certificate files when clicked.
See your browser help system for complete instructions on how to import certificates and revocation lists.
You may also use the above CA certificate in your e-mail client software for encrypting communications with the mail server. See your e-mail software documentation for more information.