PREFLIGHTWARN1 OF 7 CHECKS

Server

Preflight

Is this installation ready to deliver mail? Run it after the first start, after moving the server, or when receivers start refusing you. Health watches what runs; Preflight checks what the outside world sees.

01

Checks

Ran 14:02 UTC · 3.1 s
CheckResultFoundWhat to do
Reverse DNSok203.0.113.25 ⇄ mail.example.org—
TLS certificatewarnValid for mail.example.org, expires in 12 daysRenewal has not run. Check that port 80 reaches the ACME client and look for acme in the system log.
Port 25ok220 mail.example.org ESMTP—
Ports 465, 587okTLS handshake, 220 banner on both—
HELO nameokmail.example.org—
Proxy headersokPeer 172.18.0.2 is trusted; X-Forwarded-Proto: https—
DKIM signingokinet:127.0.0.1:8891 answers—
Ports are dialled from inside the container at the public address; a firewall that treats inside and outside differently can make this pass while the world is still blocked. SPF, DKIM and DMARC are per domain — each outbound domain shows its own.
02

Send a test e-mail

Confirms the relay accepted it, not that it arrived

Sent from postmaster@mail.example.org through the local Postfix.

Last test
14:03 UTC to mix@elsewhere.example
Result
queued 4XcC1d8Pq2z1