Hello dear community
I have (one/several) network servers with a stupid problem.
If email is received or accepted from external addresses for a local mailbox (or alias) and that mailbox or alias is set up to be forwarded to another external address, this will fail.
The email is (apparently) forwarded using the address of the original sender. This will of course be rejected by the receiving mail server.
Unfortunately, I can’t say whether this is a general behavior of the Nethserver because I haven’t had this scenario “extern-email > Nethserver > other-extern” before.
I run Nethserver with ProxmoxMailgateway upstream and like to use a specific “local” email address, let’s say “status@my-domain.tld”, for status messages and error messages from Nethserver services and other devices in the local network.
This “local” address is stored in the Nethserver as a forwarding address (without an account) to an external address, let’s say “status@other-domain.tld” - which is on a completely different server under a different external IP. Status emails that arrive at the network server for “status@my-domain.tld” have long been reliably forwarded to “status@other-domain.tld”. Since the senders of the status emails all work “locally” behind the external IP (permissible sender IP), I have not yet noticed that the above-mentioned forwarding only works in “local” cases.
External emails that reach the net server from “status@my-domain.tld” and are then supposed to be forwarded to the external email address “status@other-domain.tld” FAIL. It doesn’t matter whether “staus@my-domain.tld” is just an alias with forwarding to an external address or exists as a real mailbox on NEthserver and should be forwarded via mailbox forwarding or as a forwarding set up in SOGo.
The reason for this is clear (as described at the beginning) because the original address (and therefore domain) is used as the sender address in the forwarding.
But why does the Nethserver do this? Does this mean that any emails received externally cannot be sent to another external address? Wouldn’t it be more correct if the sender was replaced by the address (and therefore domain) of the net server?
Addendum:
The problem apparently does not affect all external incoming emails, because “noreply-dmarc-support@google.com”, for example, is forwarded correctly.
