automatic read confirmations by e-mail import without outlook?

Hi everybody,

I am testing our e-mail migration tool which is insertig my old inbox into the new Exchange 2013 CU1 server by EWS API. Now I discovered that the serer is sending "read:" notifications for all my old e-mails although I have no Outlook active.

Is there a server side setting for this?

How can I disable that?

Thanks,

Matthias