Support NRPC Mail routing to polling server behind firewall-sending server holds for pickup

We have a domino server exposed to the internet, allowing specific customer's servers (which are behind a firewall and not directly exposed to Internet) to periodically replicate certain templates and databases we host. We would like to enhance connectivity by supporting domino mail routing via these same polled connections. Instead of using public SMTP routing, this would enhance privacy concerns by allowing simpler native notes encryption and point to point connections.

Currently customer originated e-mail to our domain will route to our public server when the periodic replication connection is established. However we are not able to send or reply to the customer because our server is not able to initiate a connection to the customer's server since it is behind a firewall without a public IP/Nat. HCL Support indicates this is a limitation and an IP# is required even though data routing is working in this environment (in other words both sides of the route must be able to initiate a connection, receive only is not supported for mail routing)

We propose that there be support that if a sending server can't initiate a connection with the configured destination server, it will hold the mail and wait for the receiving server to make the connection. The receiving server can be configured to do mail push/pull to perform the bidirectional transfer of mail in addition to data replication.

Currently in this environment, our server reports the customer's server IP# is unknown whenever there is mail pending, even though an active connection exists. We view this as a bug, but support has taken a different position on the matter.

support ticket referenced below.