Two questions — axfrdns external slaves and NodeWorx outbound email relay

I’m setting up a fresh Interworx 8 install on AlmaLinux 9 and have two questions with a common theme — I want to keep some things entirely within the Interworx ecosystem, while carving others out to existing infrastructure.

1. axfrdns with external DNS slaves

I want to use this server as a hidden master for some domains, with external DNS slaves pulling zones via AXFR. I’m well versed in doing this with BIND and have done it for years. I want this configured on a per-domain basis — not all domains hosted on this server need to go through external slaves. What I want to confirm is the correct workflow on the Interworx/djbdns side — specifically, editing the tcp file in /service/axfrdns-[IP]/ and running make. Is there anything I need to do within NodeWorx itself, or is the tcp file the whole story? Any gotchas specific to Interworx 8 on AlmaLinux 9?

2. NodeWorx outbound email relay

I have a Proxmox Mail Gateway handling outbound mail sanitation for my infrastructure and want some outbound mail from this server routed through it. DKIM is fine for SiteWorx-hosted domains since Interworx handles that automatically. The complication is with the NodeWorx domain itself — it isn’t a SiteWorx account, so it doesn’t benefit from that same automated setup, and routing it through my existing infrastructure is the cleaner solution. However, I don’t want all outbound mail going through it — SiteWorx domain mail I want to remain entirely within the Interworx ecosystem.

I found two options in the docs — SMTP Routes in the MTA UI (which appears to affect all outbound mail) and senderroutes (which appears to route by sender domain). Is senderroutes the right tool for this? And is there a reliable way to identify what domain NodeWorx system mail sends from so I can match on it correctly?