DbMail Outlook Received Date

Hello DBMail users,

I installed DBMail (1.2.3) on my server and copied a lot of emails to an 
folder in dbmail. Problem is the "received date", that is shown by 
email-clients. When using clients like thunderbird or kmail everything 
works fine. But some users still use Outlook as email-client. In Outlook 
the received date is wrong. Outlook shows the date, when the email is 
copied into the dbmail server (the value of "internal_date" in table 
messages). I tried the same thing with an another IMAP-Server (Cyrus) 
and there it works with the "original" receive date of the email.

Is this a problem of Outlook, or why does dbmail sends this date to the 
client? Perhaps you have an idea how to solve this. It is not very nice 
to have 5000 mails with the same date in one folder. :-)

Greetings,
Ronny