SmartRelay headers, identifiers attributes and error codes

421 Reconfiguration in progress

421 Service unavailable, concurrency limit reached

452 Service unavailable, recipients per message limit reached

501 RCPT TO syntax error

550 Relaying denied

clabDeliveryId

clabDeliveryLabel

clabExternalDesc

clabExternalId

clabPrimaryKey

clabRecipient

X-Clab-SmartRelay-DeliveryId

X-Clab-SmartRelay-DeliveryLabel

X-Clab-SmartRelay-ExternalDesc

X-Clab-SmartRelay-ExternalId

X-Clab-SmartRelay-NewDeliveryType

X-Clab-SmartRelay-PrimaryKey

X-Clab-SmartRelay-Recipient-

X-Clab-SmartRelay-Track

X-Clab-SmartRelay-TrackingDomain

X-Clab-SmartRelay-TrackingDomainLink

X-Clab-SmartRelay-TrackingDomainView

X-Clab-SmartRelay-TrackLink

X-Clab-SmartRelay-TrackView

X-Clab-SmartRelay-UnsubscribeDomain