These are most of the webs checked to make the guide. Some of them may exist in the future, some of they won’t, but they all are worth to be mentioned:

Configuring postfix – tldp.com : http://www.tldp.org/HOWTO/Postfix-Cyrus-Web-cyradm-HOWTO/postfix-config.html

Postfix/master.cf – HTYP: http://htyp.org/Postfix/master.cf

Postfix mail server limit the mailbox size : http://www.cyberciti.biz/tips/postfix-mail-server-limit-the-mailbox-size.html

Linux postfix SMTP : http://www.cyberciti.biz/tips/postfix-smtp-ssl-certificate-csr-installation-guide.html

Postfix configure anti spam with blacklist : http://www.cyberciti.biz/tips/postfix-spam-filtering-with-blacklists-howto.html

IntegratedSpamdInPostfix – SpamAssassin Wiki : http://wiki.apache.org/spamassassin/IntegratedSpamdInPostfix

Fighting Spam with SpamAssassin and Postfix : http://www.akadia.com/services/postfix_spamassassin.html

SpamAssassin – Using pyzor:  http://wiki.apache.org/spamassassin/UsingPyzor

SpamAssassin – Using SQL : http://wiki.apache.org/spamassassin/UsingSQL

Automatically purge old emails – Kolab Wiki : http://wiki.apache.org/spamassassin/UsingSQL

Sieve server-side mail filtering with Postfix, Dovetot – Koansys : http://koansys.com/tech/sieve-server-side-mail-filtering-with-postfix-dovecot

Sieve (mail filtering language) – Wikipedia : http://en.wikipedia.org/wiki/Sieve_%28mail_filtering_language%29

SpamAssassin README: http://cpansearch.perl.org/src/FELICITY/Mail-SpamAssassin-3.0.2/sql/README.bayes

Instalando un antispam con SpamAssassin y Postfix : http://www.imaginanet.com/blog/instalando-un-antispam-con-spamassassin-y-postfix.html

PHP-FPM, application server made by PHP : http://publications.jbfavre.org/web/php-fpm-apps-server-nginx.en

PHP with a PHP APC Opcode Cache: http://www.brandonturner.net/blog/2009/07/fastcgi_with_php_opcode_cache/