I needed postfix to handle virtual domains contained in a MYSQL database. Postfix is by default not compiled with MySQL support. I'll provide 2 options. The first option is to install it using yum from my repo. The second option is to compile it yourself.
First you need to add my repo to yum.
> cd /etc/yum.repo.d
> wget www.campworld.net/repos/FC8/campworld.repo
Now install Postfix.
> yum install postfix
First you need to download the postfix source from www.wl0.org and install them.
> wget http://ftp.wl0.org/official/2.4/SRPMS/postfix-2.4.5-3.src.rpm
> rpm -ihv postfix-2.4.5-3.src.rpm
Next generate a new SPEC file.
> cd /usr/src/redhat/SOURCES
> export POSTFIX_MYSQL_REDHAT=1
> export POSTFIX_SASL=2
> export POSTFIX_LDAP=0
> chmod 744 make-postfix.spec
> ./make-postfix.spec
Finally lets compile and install the rpm.
> cd /usr/src/redhat/SPECS
> rpmbuild -ba postfix.spec
> cd /usr/src/redhat/RPMS/i386
> rpm -ivh postfix-2.4.5-3.mysql.sasl2.fc8.i386.rpm
Whichever option you chose, you now have mysql support in postfix.