SMTP reply codes

The list below is a standard list with the SMTP reply codes according to the SMTP standard. Beware however that this is just a standard, and that certain SMTP servers might return their own status, codes and descriptions that differ from the list below.

Code Status (SMTP Error) Description
211 2.1.1 System status, or system help reply
214 2.1.4 Help message
220 2.2.0 Service ready
221 2.2.1 Service closing transmission channel
250 2.5.0 Requested mail action okay, completed
251 2.5.1 User not local; will forward to <forward-path>
354 3.5.4 Start mail input; end with <CRLF>.<CRLF>
421 4.2.1 <domain> Service not available, closing transmission channel
450 4.5.0 Requested mail action not taken: mailbox unavailable
451 4.5.1 Requested action aborted: local error in processing
452 4.5.2 Requested action not taken: insufficient system storage
500 5.0.0 Syntax error, command unrecognised
501 5.0.1 Syntax error in parameters or arguments
502 5.0.2 Command not implemented
503 5.0.3 Bad sequence of commands
504 5.0.4 Command parameter not implemented
521 5.2.1 <domain> does not accept mail
530 5.3.0 Access denied
550 5.5.0 Requested action not taken: mailbox unavailable
551 5.5.1 User not local; please try <forward-path>
552 5.5.2 Requested mail action aborted: exceeded storage allocation
553 5.5.3 Requested action not taken: mailbox name not allowed
554 5.5.4 Transaction failed