We're running PHP5.3.8 on a CentOS6.6 mailserver with Postfixadmin 2.3rc5. The client only wanted a mailserver at first, but then wanted to move some other sites to this server. Some of the sites need PHP5.4 to run, but we're afraid that upgrading from PHP5.3 to PHP5.4 will break our Postfixadmin installation. (We found some info that postfixadmin is compatible with php5.4 from version 2.3.5) Also, upgrading Postfixadmin will likely break the database and we can't afford downtime.
What is the best approach to this issue? Multiple PHP versions? Has anyone upgraded such an old postfixadmin version to a new one? Has anyone succesfully installed php5.4 with an older version of Postfixadmin?