SMTP code 550 SC-002
What the knowledge base's own tables say about this code, and which articles say it — a description of the reply, never a placement prediction.
This line comes from a knowledge base article on Microsoft, not on the standard.
- Meaning
- Namespace mining behavior detected
- Next step
- Verify machines aren't compromised; stop address-harvesting
From Microsoft Outlook.com Sender Requirements · SMTP error codes