Knowledge base
domain-key<virtual-mta>criticalset by the HubDirectiveStream keys are stronger than general ones: when both levels match, these win.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.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.cold-virtual-mta<virtual-mta>DirectiveNames the cold sending address; how many messages it gets is set by a separate directive in the receiver block.include-headers-from<virtual-mta>DirectiveThe same line as at the node level; set here, it does not replace the common one but adds to it.max-smtp-msg-rate<virtual-mta>DirectiveThe only rate limit that counts the sending address as a whole rather than each queue separately.max-smtp-out<virtual-mta>set by the HubDirectiveThe overall ceiling of the sending address. Without the line there is none at all — queues add up without limit.proxy-include-tlv<virtual-mta>set by the HubDirectiveAdds a field with the queue domain to the PROXY header; requires the second protocol version.proxy-protocol<virtual-mta>set by the HubDirectiveThe HAProxy header version, 1 or 2; the default is the first.smtp-proxy-source-host<virtual-mta>set by the HubDirectiveThe same directive written inside a sending address; it replaces the node’s common setting and forbids the regular form and use-proxy in the same block.suppression-lists<virtual-mta>DirectiveThe same line as in a source, but here there is no choice — the message is always accepted, queued and bounced.use-proxy<virtual-mta>DirectiveA list of proxy blocks in backup order; the second is used only when the first did not respond.include<virtual-mta>DirectiveThe same directive written inside a sending address — the included lines become its settings.max-smtp-data-volume-rate<virtual-mta>DirectiveThe only ceiling that counts volume rather than messages — and only the volume that got through.rewrite-list<virtual-mta>DirectiveAttaches a named list; messages leaving through this sending address go through its rules.