postinst is in squirrelmail-logger 2.3.1-1.
This file is a maintainer script. It is executed when installing (*inst) or removing (*rm) the package.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15  | #!/bin/sh
set -e
case "$1" in
	configure)
		squirrelmail-configure --remove-plugin squirrel_logger
		squirrelmail-configure --install-plugin squirrel_logger
	;;
	*)
	;;
esac
exit 0
 |