Not clear how to configure hashmail when unable to bind to external IP

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As explained here https://docs.lightning.engineering/lightning-network-tools/aperture/mailbox#docs-internal-guid-6f5d734c-7fff-7276-2045-8790bdb8ac96 , it is not possible to bind to the external IP used in many VPS setups. This is because it's behind NAT and the external IP doesn't terminate on the VM.

My question is, is it possible to use the hashmail feature of aperture with this networking setup? Part of the solution is to set `listenaddr: "0.0.0.0:443"` to bind to an externally accessible interface, but when I do this I get the following error when trying to connect via lnc:

`[DBG] PRXY: No backend service matched request [lightning.brodie.rocks:443/hashmailrpc.HashMail/RecvStream].`

I'm guessing the problem is no service is defined for that FQDN because it is bound to 0.0.0.0 ? I looked through how to configure services but it all seems geared towards LSAT configuration, where in this case I'm only interested in setting up a hashmail proxy.

aperture.yaml used:
`listenaddr: "0.0.0.0:443"
debuglevel: "trace"
autocert: false
servername: lightning.brodie.rocks
authenticator:
disable: true
hashmail:
enabled: true
messagerate: 1ms
messageburstallowance: 99999999
prometheus:
enabled: false`

Thanks for any tips/suggestions.

Start with the linked hashmail documentation and the service-configuration entry points, using the supplied aperture.yaml and lnc connection to reproduce the "No backend service matched request" error. Determine whether hashmail can operate behind NAT with listenaddr set to 0.0.0.0, and document the supported configuration or the limitation clearly.

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