Each of the packages above is a compressed tar file. Download it, unpack it (with "tar xzvf <filename>.tar.gz") and run the "install.sh" script in it.
The Change Log lists all the updates, additions, fixes and other changes that have happened to MailScanner. Check here to see whether you might want to upgrade to the latest version, by reading the lists of new features and changes to find if any of them affect you.
Find my PGP public key here: http://pgp.mit.edu:11371/pks/lookup?search=Julian+Field&op=index Yes, I know that's not a link. Anyone who compromised this site could change the link and you probably wouldn't notice. Cut and paste it into your web browser.