| LogBud | SMTP query |
| Numeric Order List of Reply Codes 211 System status, or system help reply 214 Help message (Information on how to use the receiver or the meaning of a particular non-standard command) 220 <domain> Service ready 221 <domain> Service closing transmission channel 250 Requested mail action okay, completed 251 User not local; will forward to <forward-path> 354 Start mail input; end with <CRLF>.<CRLF> 421 <domain> Service not available, closing transmission channel (This may be a reply to any command if the service knows it must shut down) 450 Requested mail action not taken: mailbox unavailable 451 Requested action aborted: local error in processing 452 Requested action not taken: insufficient system storage 500 Syntax error, command unrecognized (This may include errors such as command line too long) 501 Syntax error in parameters or arguments 502 Command not implemented 503 Bad sequence of commands 504 Command parameter not implemented 550 Requested action not taken: mailbox unavailable ([E.g., mailbox not found, no access) 551 User not local; please try <forward-path> 552 Requested mail action aborted: exceeded storage allocation 553 Requested action not taken: mailbox name not allowed (E.g., mailbox syntax incorrect) 554 Transaction failed Other RFC mail-related resources: RFC822 Mail header format RFC974 MX routing RFC976 UUCP mail format RFC1123 Host requirements (modifies 821, 822, and 974) RFC1413 Identification server RFC1869 SMTP Service Extensions (ESMTP spec) RFC1652 SMTP Service Extension for 8bit-MIMEtransport RFC1870 SMTP Service Extension for Message Size Declaration RFC2045 Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies RFC1344 Implications of MIME for Internet Mail Gateways RFC1428 Transition of Internet Mail from Just-Send-8 to 8-bit SMTP/MIME RFC1891 SMTP Service Extension for Delivery Status Notifications RFC1892 Multipart/Report Content Type for the Reporting of Mail System Administrative Messages RFC1893 Enhanced Mail System Status Codes RFC1894 An Extensible Message Format for Delivery Status Notifications RFC1985 SMTP Service Extension for Remote Message Queue Starting RFC2033 Local Mail Transfer Protocol (LMTP) RFC2034 SMTP Service Extension for Returning Enhanced Error Codes RFC2476 Message Submission RFC2487 SMTP Service Extension for Secure SMTP over TLS RFC2554 SMTP Service Extension for Authentication | ||||||||||||||||||||||||||||||||
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