None of my VirtualBox systems will forward mail. The mails move immediately from /var/mail to the mqueue directory and sit there forever.
Forwarding works fine with my four real machines.
The only clue I saw was in the mail logs that the connection timed out.
This all worked just fine not long ago. I don't know when the forwarding stopped. Is there anything special that needs to be done with VirtualVox?
NFS mounts, rwall, telnet, and ssh all work fine, both directions.
Yes, I tested with no iptables firewall.