Notes/Domino 6 and 7 Forum : Mail routing still doesn't work... Domino Experts plz help..

Here's the story:

Our IT policy doesn't allow incoming connections on 1352, not even from the host on the ISP segment. The setup we're trying to create is actually to avoid connections from the internet to our infrastructure, but we still want to give road-warriors access to their mailboxes. So we put a server at an ISP.

All mailboxes live on server A (the server at the office)and only a couple of mailboxes are being replicated from A to B (the server placed by the isp). Replication between the mailfiles is going fine. SMTP from server B to send mail to internet addresses is working fine too.

However, sending mail to a user who's mailbox resides on B. Doesn't work.
We just tried the Pull-Push vs Pull-Wait setup, but when I send an email from server B to a mailbox that resides on A, the mail router can't seem to deliver the mail to mail.box, because it can't connect to the destination server. This is pretty strange, because B should wait for a Pull request from A, not?
At first, I forgot to fill in an IP (because B shouldn't connect on it's own), but then the message couldn't be delivered, because the destination server was an unknown TCP/IP host..

Is there maybe an additional port Notes uses for routing (besides tcp 1352)

Anyway, I don't know what's wrong..

Thanks in advance,

Wiard