ptload error in syslog when receiving mails to secondary email addresses

[Matthias Busch]

kolab 3.3 on debian 7.6 x64, single domain, all ssl enabled with 
ca-signed ssl certificate

I am getting the following error in syslog:

Nov  7 14:58:41 kolab ptloader[4154]: No entries found
Nov  7 14:58:41 kolab lmtpunix[5094]: ptload(): bad response from 
ptloader server: identifier not found
Nov  7 14:58:41 kolab lmtpunix[5094]: ptload failed for primary at domain.tld
Nov  7 14:58:41 kolab lmtpunix[5094]: Delivered: 
<545CD00D.3070605 at gmx.net> to mailbox: domain.tld!user.primary

when an email is received for alias at domain.tld

(alias=secondary email)

the email is being delivered so its not critial...

I thought I had seen the last of those ptload errors, apparently I was 
wrong...

Unfortunately I have other trouble with freebusy/wallace and this is 
probably unrelated (although freebusy can and does cause ptload errors 
for me too), but I want to be sure and not have misconfigured software 
running on a production server

What could be causing it? and how concerned should I be?