Exact response pattern
211 System status, or system help replyInfoGenericProtocol
What it means
The server is returning system status or help information rather than accepting a message.
Likely causes
- A client issued HELP or a status command.
Recommended response
- Review the returned capabilities or help text.
- Continue with the correct SMTP command sequence.
Operational rule: Preserve the complete SMTP response, remote hostname, sending IP, envelope sender and timestamp. Never diagnose from the three-digit code alone.