Seeing an issue with imap-proxy in a Split DNS setup.
Server A: Master LDAP/MTA/mailstore
Server B: LDAP replica/MTA/mailstore/proxy
B is behind firewall, configured with Split DNS. Server A sees B at external IP xx.xx.xx.1 and B seems its IP as 192.168.1.xx. DNS is configured correctly. No, really.
Client connecting to B with mailbox on B (so, to itself) sometimes works and sometimes fails. When it fails, nginx.log on B shows:
[error] 28730#0: *55 recv() failed (110: Connection timed out) while reading response from upstream, client: 192.168.1.xx, server: 0.0.0.0:993, login: "test_user@domain", upstream: xx.xx.xxx.1:7143, [192.168.1.xx:52223-192.168.1.xx:993] <=> [192.168.1.xx:53649-0.0.0.0:0]
Setting client to hit port 7993 (direct to imaps) works correctly.
Why is B trying to proxy to its external IP? I verified via tcpdump that it is trying (and failing).