SMTP 211 System Status vs 554 Transaction Failed
SMTP 211 (System Status) is a 2xx Positive Completion response, while 554 (Transaction Failed) is a 5xx Permanent Negative response. 211 indicates that a system status reply providing information about the mail server's current state. This is typically sent in response to a HELP or system inquiry command. In contrast, 554 means that the mail transaction has failed. This is a catch-all permanent error that can occur at any point during the SMTP session, including as a rejection greeting when the server refuses all connections from
คำอธิบาย
A system status reply providing information about the mail server's current state. This is typically sent in response to a HELP or system inquiry command.
เมื่อคุณพบเห็น
When querying the mail server for its status or capabilities. The server is sharing diagnostic or informational details about itself.
วิธีแก้ไข
No fix needed — this is an informational response. If the status indicates a problem, review the server's configuration or contact the mail administrator.
คำอธิบาย
The mail transaction has failed. This is a catch-all permanent error that can occur at any point during the SMTP session, including as a rejection greeting when the server refuses all connections from your IP.
เมื่อคุณพบเห็น
When the entire mail transaction is rejected — often due to spam filtering, blacklisted IP addresses, malformed messages, or policy violations detected during the DATA phase.
วิธีแก้ไข
Check your IP against DNS blacklists (DNSBL) and verify your SPF, DKIM, and DMARC records. Review the full error message for specific rejection reasons. If blacklisted, request delisting from the relevant blocklist.
ความแตกต่างหลัก
211 is a 2xx Positive Completion response, while 554 is a 5xx Permanent Negative response.
SMTP 211: A system status reply providing information about the mail server's current state. This is typically sent in response to a HELP or system inquiry command.
SMTP 554: The mail transaction has failed. This is a catch-all permanent error that can occur at any point during the SMTP session, including as a rejection greeting when the server refuses all connections from
You encounter 211 when when querying the mail server for its status or capabilities. The server is sharing diagnostic or informational details about itself.
You encounter 554 when when the entire mail transaction is rejected — often due to spam filtering, blacklisted IP addresses, malformed messages, or policy violations detected during the DATA phase.
ควรใช้อันไหนเมื่อไร
For 211 (System Status): No fix needed — this is an informational response. If the status indicates a problem, review the server's configuration or contact the mail administrator. For 554 (Transaction Failed): Check your IP against DNS blacklists (DNSBL) and verify your SPF, DKIM, and DMARC records. Review the full error message for specific rejection reasons. If blacklisted, request delisting from the relevant blocklist.