Send email issue: messages remain in postfix queue.

Hi, I've succesfully deployed on my win8.1 workstation a "turnkey-magento-13.0-wheezy-amd64" virtual machine for some test.

I've some problem sending e-mails, i.e. e-mails sent by the registration process on Magento website remain in the postfix queue with this error:

"Host or domain name not found. Name service error for name=mysite.com type=MX: Host not found, try again"

where "mysite.com" is the real domain name of my business!

The guest VM is hosted by VMware Player 6.0.3 build-1895310; it is connected with host's NIC with BRIDGE protocol and IP address, netmask and DNS of the VM are set correctly.

Any ideas?

Thanks, Andrew.