in config/main.inc.php
search for
// these cols are shown in the message list
// available cols are: subject, from, to, cc, replyto, date, size, encoding
in the following line
$rcmail_config['list_cols'] = array('subject', 'from', 'date', 'size');
define your preferred order, in your case
$rcmail_config['list_cols'] = array('from', 'subject', 'date', 'size');