smtp-sink-address verified
Send every connection here instead
smtp-sink-address: Redirects the TCP connection of every delivery to one address, while the rest of the engine behaves as though the mail were going to its real destination.
Values
- Values
address or hostname- Default
· taken from the build- applying
restart required- where it can be set
in the config file · with a startup flag · as an environment variable
In detail
The most useful directive in the product for anyone studying it, and the one that made this catalogue's address measurements possible. Queues, limits, DNS, DKIM signing and result reporting all carry on normally — only the connection goes somewhere else. So a delivery result names the real receiving server while the message itself lands in the sink. That is also its danger: a node with a sink configured looks entirely healthy. Statistics show deliveries, results say accepted, the console is green — and not one message reached a recipient. Anyone inheriting a node should check for this before believing its numbers. DNS still applies: a domain that does not resolve fails before a connection is attempted, so the sink never sees it. We watched exactly that happen with a domain that had no mail server.