I have finally updated my Postfix howto!
It is now based on Ubuntu 8.04 Hardy Heron. And as before includes detailed, easy to follow instructions of building a mail server using Postfix, Courier, MySQL, amavisd, SpamAssassin, ClamAV, SASL, TLS and SquirrelMail.
It is not quite finished yet however, but I would recommend following it rather than the old one. But keep referencing the old one as it has a lot of detail. The new howto, edition 7, does at the moment only include the core packages, but enough to get a advanced and secure server up. For any extensions and further info it still referes to the old edition (5). But I will keep padding it out with old and new content.
New for this edition is the inclusion of Amazon Elastic Computing Cloud(EC2) as reference build of the server. I have also made public AMIs for people to launch and customize if they so choose.
Hope it is of use to people!