If you want a 100%-according-to-your-needs package, the solution is to recompile postfix from source using a modified .spec file.
Before compiling the postfix package to support SASL, MySQL lookup tables and virtual users, some development tools must be installed.
First, the postfix source must be downloaded. Since I prefer keeping CentOS package versions, I've used the postfix source RPM, available at CentOS mirrors, in the directory ./os/SRPMS/. You must also download the VDA patch from http://vda.sourceforge.net, to enable virtual delivery agent for postfix, it is required for virtual users support.
Modify /usr/src/redhat/SPECS/postfix.spec file to enable SASL and MySQL (and/or Postgresql if required). The main differences are: Cyrus-SASL support removed, MySQL support added, set default SASL to "dovecot", postfix-vda patch included. Use the postfix.spec.diff attached below, upload it to /usr/src/redhat/SOURCES, and apply the patch:
Now you are ready to build the package:
The first command builds a .rpm package, you'll find it on /usr/src/redhat/RPMS/architecture/postfix-2.3.3-2.1.i386.rpm
The second command builds a .src.rpm package, you'll find it on /usr/src/redhat/SRPMS/postfix-2.3.3-2.1.src.rpm, it contains all the modified and added files (VDA patch, the modified postfix.spec file), you may need it later.
Now you can install the package:
After installing the package, probably you should add it to [base] and [updates] sections 'excludepkgs' list in /etc/yum-repos.d/CentOS-Base.repo, so an upgrade won't mess your system.
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