Hello all, TL;DR: `sendmail <address>` fails with `sendmail: fatal: could not find any active network interfaces` if loopback interface is not up. Is this expected behaviour?
Longer: I know applications can expect the loopback interface to be available. However, strictly speaking, sendmail when invoked for local mail submission shouldn't attempt to access the network, all it has to do is drop the file into the maildrop directory. It shouldn't have open any kind of network socket, and indeed it does work even with postfix daemon stopped. The background for this werid question, by the way, is that I was poking about an application I have, and I wanted to see what would happen if I ran it without internet access. The expected outcome was that it'd gracefully fail and send me a nice e-mail with a notification - which would be delivered whenever the site got internet access back. So I ran it with unshare --net myapp And got this outcome instead. Thoughts?
