Settings › Overview, Delivery strategy and Routes offer a guide ("Guided
or manual?" each time) that:
- checks port 25 from this server with the Delivery tests probe (MX
lookup, connection, greeting; nothing is sent) and recommends direct
delivery or a relay from the result;
- sets up a relay from presets: Amazon SES (by region), Mailgun (US/EU),
SendGrid, Postmark, Brevo, SMTP2GO or any other server, with where to
find each one's SMTP credentials and what to verify first;
- shows every change in plain words before writing it: a Relay route
named relay, the route fallback pointed at it (local delivery and any
other rules untouched), and, for a STARTTLS relay, a relay-tls strategy
with STARTTLS required for that host, so the password never goes out
unencrypted. Implicit TLS on 465 wherever the service offers it;
- writes it step by step and puts back what it wrote if a later step is
refused;
- ends with how to test it: send from webmail, watch Outbound delivery
and the queue.
Running it again edits the saved relay (an empty password keeps the
saved one), or switches back to direct delivery, which also drops the
relay's TLS rule.
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