Web search for Ubuntu mail server tutorials

I want to setup a mail server running under Ubuntu. I'm thinking about a configuration containing Dovecot IMAP or Courier IMAP, Postfix SMTP, Postgrey, and SpamAssassin. Currently, I'm searching and sorting tutorials on this topic. These are the most promising I found so far:

• http://www.howtoforge.com/virtual-users-and-domains-postfix-dovecot-mysql-centos4.5
• http://johnny.chadda.se/2007/04/15/mail-server-howto-postfix-and-dovecot-with-mysql-and-tlsssl-postgrey-and-dspam/
• http://www.debianadmin.com/how-to-filter-spam-with-spamassassin-and-postfix-in-debian.html
• http://www.debuntu.org/postfix-and-postgrey-a-proactive-approach-to-spam-filtering
• http://johnny.chadda.se/2007/04/15/mail-server-howto-postfix-and-dovecot-with-mysql-and-tlsssl-postgrey-and-dspam/
• http://piao-tech.blogspot.com/2007/03/add-encryption-to-smtp-and-pop-tlsssl.html
• http://theclimber.fritalk.com/post/2009/01/27/Tutorial-:-Setup-your-mail-server-(courier-imap-postfix-postgresql)