Tried ius and utterramblings, used the replace yum plugin.
In all cases squirrelmail refused to work.
with ius, it claimed in the browser that config.php was not present. Worse with php53u there was no reaction, just acted as if the soft links it needed was not there and failed to function.
The wreckage in this case is the left column of SM, with this errorr:
ERROR: Could not complete request.
Query: CREATE "Sent"
Reason Given: Invalid mailbox name.
In spite of following the instructions in http://www.howtoforge.com/perfect-se...ispconfig-3-p6
for correcting that error.
I think this is a worthy experiment to work on, I think it can be done.
I would suggest though that the entire process for building perfect server with php 5.3 be cooked and tested. I know its a lot of work, but let me put this premise out.
A lot of folks including myself use ISPCONFIG3 to stand up word press and Joomla websites. Both of those now require php 5.2.4 or above to stay current. It is probably time for that configuration to simply include a migration to php 5.3.
Please feel free to contact me email and let me know how to help.
I'm going to stand up a VM to play with and keep pounding this until it works.