If someone want to use Postfixadmin (like rc7), not shipped within iRedMail - it doesnt work by default.
The database sheme is different.
To get Postfixadmin to work, you have to add a column in the mailbox table:
ALTER TABLE `mailbox` ADD `local_part` VARCHAR( 255 ) NOT NULL AFTER `domain` ;
It´s not a cleanly solution but Postfixadmin works. This column isn´t used by iRedMail.
Better solution would be change some function in PFA but I hadn´t time enough to find it out, was painful enough!