OK, I'm partly confused. The goal is to get a job from Domain Σ into Domain A without much fanfare, but the only way to get from Σ into A is via email or file share. Hrmmm.
I'm confused because file share and print share both use RPC, which implements TCP 445 and is already allowed through the firewall. So in theory, Σ machines can connect to shares on A, they'd just need to provide their A credentials on initial connection. If the PrintScout is installed on their Σ computer, it would pick up the A credential at print so the user would only need to authenticate at the Pharos terminal-controlled device to see jobs and release them.
Am I missing something?
Thanks for the follow-up!
Unfortunately, the firewall does not allow for TCP 445 to pass through. Instead, a kind of transfer proxy is implemented. Difficult to find an analogy but think of it as floppy drives that put into Σ side, then the data is moved onto them and then is moved into A. Deparments, hundreds of them, have their own outgoing and incoming directories with the DXXXXX name. What you put in the outgoing you get from incoming a bit later. This is the way it is in this client.
seems we have finally made a progress on the subject. The client considers IMAP as an exception for a server-server communications.