So, I managed to solve it myself. Turned out to be a problem with ISPmanager unable to convert the .Maildir to mbox (seems like ISPmanager defaults to mbox format on a fresh install on CentOS?) format on the target machine.
I had to add
Code:
Option Procmail
Option MailDir
to ispmgr.conf
and change procmail's defaults to Maildir too..
/etc/procmailrc:
Code:
MAILDIR=$HOME/.maildir
DEFAULT=$MAILDIR/
so, i have it solved for now, but that doesnt change the fact that ISPmanager was unable to convert the mailboxes... perhaps you should check those routines