EC
211
SMTPINFOCriticalSystem InformationHIGH confidence

System status, or system help reply

What this means

The 211 code provides a system status update or a help reply. It is returned by an SMTP server in response to a client's request for status or help information.

Why it happens
  1. 1The client sent a `HELP` command to the server.
  2. 2The client sent a `STAT` command to query the server's status.
  3. 3The server is configured to provide specific diagnostic information upon request.
How to reproduce

A client sends a HELP command to get information about the commands the server supports.

trigger — this will error
trigger — this will error
HELP
211-Supported commands:
211-EHLO
211-MAIL
211-RCPT
211-DATA
211-QUIT
211-HELP

expected output

211 System status reply

Fix

Parse the multi-line system status response

WHEN When scripting against an SMTP server and you need server status

Parse the multi-line system status response
telnet mail.example.com 25
# Lines prefixed 211- are continuation lines
# Final line starts with "211 " (space, not dash)

Why this works

The 211 response may span multiple lines (211- for continuations, 211 space for the final). Parse until the space-delimited line to capture the full reply.

What not to do

✕ Rely on 211 for production delivery logic

HELP/STAT are informational only. Content and format vary widely between server implementations.

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