SMTP Reply codes are used to determine the error in the message, SMTP(Simple Mail Transfer Protocol) is a standard protocol for sending emails, the client sends and the server responds, a response is with the 3 digit code which contains the meaning for the response with the codes, find the below SMTP reply codes
SMTP Reply codes
Code | Description |
211 | System status, or system help reply. |
214 | Help message. |
220 | Domain service ready.Ready to start TLS. |
221 | Domain service closing transmission channel. |
250 | OK, queuing for node node started. Requested mail action okay, completed. |
251 | OK, no messages waiting for node node. User not local, will forward to forwardpath. |
252 | OK, pending messages for node node started. Cannot VRFY user (e.g., info is not local), but will take message for this user and attempt delivery. |
253 | OK, messages pending messages for node node started. |
354 | Start mail input; end with .. |
355 | Octet-offset is the transaction offset. |
421 | Domain service not available, closing transmission channel. |
432 | A password transition is needed. |
450 | Requested mail action not taken: mailbox unavailable. ATRN request refused. |
451 | Requested action aborted: local error in processing. Unable to process ATRN request now |
452 | Requested action not taken: insufficient system storage. |
453 | You have no mail. |
454 | TLS not available due to temporary reason. Encryption required for requested authentication mechanism. |
458 | Unable to queue messages for node node. |
459 | Node node not allowed: reason. |
500 | Command not recognized: command. Syntax error. |
501 | Syntax error, no parameters allowed. |
502 | Command not implemented. |
503 | Bad sequence of commands. |
504 | Command parameter not implemented. |
521 | Machine does not accept mail. |
530 | Must issue a STARTTLS command first. Encryption required for requested authentication mechanism. |
534 | Authentication mechanism is too weak. |
538 | Encryption required for requested authentication mechanism. |
550 | Requested action not taken: mailbox unavailable. |
551 | User not local; please try forwardpath. |
552 | Requested mail action aborted: exceeded storage allocation. |
553 | Requested action not taken: mailbox name not allowed. |
554 | Transaction failed. |
See Also
Simple Mail Transfer Protocol (SMTP) Enhanced Status Codes Registry – https://www.iana.org/assignments/smtp-enhanced-status-codes/smtp-enhanced-status-codes.xhtml
IP subnet calculator – https://computercarriage.com/2021/06/03/simple-ip-calculator-subnet-using-korn-shell-script-v1-0/
Shell script basics – https://computercarriage.com/2020/12/06/shell-script-basics/
rfc5248 – https://datatracker.ietf.org/doc/html/rfc5248
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