Knowledge base
always-allow-relayingGlobalcriticalset by the HubDirectiveThe very reason a node sends mail at all — and the thing that makes it an open relay if granted to the wrong source.bounce-after<domain>criticalset by the HubDirectiveUntil this point the message lives in the queue and takes up disk space.client<proxy>criticalDirectiveThe sending address the proxy must use; together with server, these are the block’s two required lines.default-virtual-mta<source>criticalset by the HubDirectiveApplies when the stream has not been chosen by anything higher up — a header, a rule or a merge variable.disable-acct-records<domain>criticalDirectiveDisables the creation of accounting records of the chosen types — delivery, bounce, transient failure, queuing failure — for an individual queue.dkim-sign<domain>criticalset by the HubDirectiveTurns signing on for the receiver; the key itself is chosen by the sending domain from the message headers.domain-key<virtual-mta>criticalset by the HubDirectiveStream keys are stronger than general ones: when both levels match, these win.domain-keyGlobalcriticalDirectiveLinks a selector, a domain and a private key; the first entry whose domain matches or is a parent domain wins.enable-source-ip-limits-on-sending-ip<domain>criticalDirectiveImportant when sending through a proxy: the local address and the one the receiver sees are different.host-nameGlobalcriticalDirectiveThe first name is the main one; which one ends up in the greeting is decided by a five-step resolution.host-name<virtual-mta>criticalDirectiveThe same directive written inside a sending address; it overrides the node’s general name but yields to the name tied to the address itself.http-accessGlobalcriticalset by the HubDirectiveA list of addresses and access levels for the management interface; closed to everyone by default.http-api-keyGlobalcriticalset by the HubDirectiveA key in the X-API-Key header grants administrator rights from any address; the line is repeatable.max-msg-rate<domain>criticalset by the HubDirectiveIt counts both deliveries and bounces — this is not “successful messages per hour.”max-smtp-out<domain>criticalset by the HubDirectiveThe main lever of pressure on the receiver: it sees the limit multiplied by the number of your addresses.postmasterGlobalcriticalDirectiveOne of the two settings the engine does not work without: the watchdog sends crash and license expiration reports here, and mail to service addresses is forwarded here as well.process-x-dkim-key<source>criticalDirectiveA permission for the source: with it, the engine takes the private key straight from the X-DKIM-Key header, signs with it and strips the header; without it, the key travels to the recipient.process-x-virtual-mta<source>criticalset by the HubDirectiveA permission for the source — with it the header selects the stream and is stripped before delivery; without it the header does nothing and travels to the recipient.record-fields<acct-file>criticalset by the HubDirectiveThe field list for one record type; the default is the star, meaning the default field set marked in the manual’s tables; it supports exclusions and arbitrary message headers.records<acct-file>criticalset by the HubDirectiveA list of eight possible accounting record types; the default is deliveries and local bounces.retain-x-dkim-key<source>criticalDirectiveThe only source block directive for which the manual prints its warning in bold: with true, the private key travels to the recipient.retry-after<domain>criticalset by the HubDirectiveIt can be set as a sequence: 10m, 1h, 4h — and then the pauses grow from attempt to attempt.run-as-rootGlobalcriticalDirectiveMust be false to run as an unprivileged user; changing it requires a restart.server<proxy>criticalDirectiveWhere the node connects instead of the receiving server; together with client, these are the block’s two required lines.smtp-listenerGlobalcriticalset by the HubDirectiveIf no listener is declared, the node silently brings one up on 0.0.0.0:25.smtp-proxy-source-hostGlobalcriticalDirectiveThe vendor’s way to send through a proxy — local address, proxy, client address and greeting name in one line.smtp-service<source>criticalset by the HubDirectiveTurning it off closes submission for the source without touching the others.smtp-source-hostGlobalcriticalDirectiveBinds outgoing connections to a local address or CIDR range and sets the name in the SMTP greeting.smtp-source-host<virtual-mta>criticalset by the HubDirectiveThe same directive written inside a sending address — it is what makes that address a separate sending identity.total-max-smtp-outGlobalcriticalset by the HubDirectiveKicks in first if a queue limit is higher; on a Standard license — silently.virtual-mta<virtual-mta-pool>criticalset by the HubDirectiveThe line lists a sending address in a pool; without a number the members are used round-robin, with a number — in the given proportion, and the shares must add up to 100.