diff --git a/docs/content/examples/use-cases/bind-smtp-network-interface.md b/docs/content/examples/use-cases/bind-smtp-network-interface.md index 32d09302..b12e21de 100644 --- a/docs/content/examples/use-cases/bind-smtp-network-interface.md +++ b/docs/content/examples/use-cases/bind-smtp-network-interface.md @@ -12,8 +12,9 @@ hide: If your Docker host is running multiple IPv4 and IPv6 IP-addresses, it may be beneficial to bind outgoing SMTP connections to specific IP-address / interface. -- When a mail is sent outbound from DMS, it greets the MTA it is connecting to with a EHLO (DMS FQDN) which might be verified against the IP resolved, and that a `PTR` record for that IP resolves an address back to the same IP. A similar check can against the envelope-sender address for SPF that verifies a DNS record like MX / A is valid (_or a similar restriction check from an MTA like [Postfix has with `reject_unknown_sender`][gh-pr::3465::comment-restrictions]_). -- If DMS connections are inconsistent with the IP used here, these DNS checks are likely to fail. +- When a mail is sent outbound from DMS, it greets the MTA it is connecting to with a EHLO (DMS FQDN) which might be verified against the IP resolved, and that a `PTR` record for that IP resolves an address back to the same IP. +- A similar check with SPF can be against the envelope-sender address which may verify a DNS record like MX / A is valid (_or a similar restriction check from an MTA like [Postfix has with `reject_unknown_sender`][gh-pr::3465::comment-restrictions]_). +- If the IP address is inconsistent for those connections from DMS, these DNS checks are likely to fail. This can be configured by [overriding the default Postfix configurations][docs::overrides-postfix] DMS provides. Create `postfix-master.cf` and `postfix-main.cf` files for your config volume (`docker-data/dms/config`).