SMTP code X.6.9
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.
- Meaning
- A message with UTF-8 headers cannot be transferred to one or more recipients, so the message is rejected
- Typical basic codes
- 550
From SMTPUTF8 / Internationalized Email (RFC 6530/6531/6532) · Relay and fallback rules, and error codes