[Druid] Delivery Status Notification (Failure)

The following message to <wladimir.raymond@statec.etat.lu> was undeliverable. The reason for the problem: 5.1.0 - Unknown address error 550-'5.1.1 <wladimir.raymond@statec.etat.lu>: Recipient address rejected: undeliverable address: host mta.mail.etat.lu[148.110.210.24] said: 550 5.1.10 RESOLVER.ADR.RecipientNotFound; Recipient not found by SMTP address lookup (in reply to RCPT TO command)'