Knowledge base
The most expensive default in the APIcriticalmechanismInterception endpoints treat a missing or misspelled target as "everything", and answer 200.Stop the mail without losing itimportantWritten by the HubprocedureHeld mail waits rather than fails — as long as the target is named and the removal matches the fields that created it.Stop delivery to a target — or to everythingimportantWritten by the HubAPI endpointHolds mail back without failing it — for one domain, one address, one tag, or for the whole cluster when the target is left out.The do-not-send listimportantWritten by the HubAPI endpointAddresses and domains the engine refuses to send to, each with the code and text it answers with.Fail mail on purpose, before it is sentAPI endpointMakes the engine answer chosen mail with a chosen SMTP error instead of delivering it.pausedstartup flagStarts the engine in a paused state — connected and configured, but delivering nothing.Paused DeliveriesimportantWritten by the Hubconsole screenHolds delivery for a target — domain or address, optionally by sending address, pool or tags — with an expiry or none.Response Patternsimportantconsole screenRules that fire on what a receiver said, with twelve actions to choose from.Suppression listimportantWritten by the Hubconsole screenAddresses and domains that are failed on sight, each with the code and text the failure carries.Forced Errorsconsole screenFails matching mail with a chosen code instead of delivering it — by destination, sending address, pool or tag.pausedcriticalWritten by the Hubdatabase tableHolds deliveries for a destination, address, pool or tag, optionally until a given time, on one node or across the cluster.suppressionscriticalWritten by the Hubdatabase tableAddresses and domains that are failed immediately, with a chosen code, checked at the moment of delivery.errorsimportantdatabase tableFails matching deliveries on purpose with a chosen SMTP code and description, and counts how often it has done so.targetcriticalWritten by the Hubdatabase fieldThe destination being held — a domain, a receiving address, or * for everything the node sends.valuecriticalWritten by the Hubdatabase fieldOne address or one whole domain that mail is never delivered to.expireimportantWritten by the Hubdatabase fieldThe moment a pause stops applying; zero means it stays until removed.codedatabase fieldThe SMTP result recorded for deliveries this rule stops.occurrencesdatabase fieldA counter the engine increments each time this forced error matches a delivery.Stopped by the suppression listimportantdelivery stateThe message was not sent because its recipient or domain is on the suppression list.