SMTP

Simple Mail Transfer Protocol

Related:
 * TCP,POP3,Email,IMAP

SMTP reply codes
Reply codes in numerical order Code 	Meaning

200	(nonstandard success response, see rfc876) 211	System status, or system help reply 214	Help message 220	 Service ready 221	 Service closing transmission channel 250	Requested mail action okay, completed 251	User not local; will forward to  354	Start mail input; end with . 421	 Service not available, closing transmission channel 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 unrecognised 501	Syntax error in parameters or arguments 502	Command not implemented 503	Bad sequence of commands 504	Command parameter not implemented 521	 does not accept mail (see rfc1846) 530	Access denied (???a Sendmailism) 535	SMTP Authentication unsuccessful/Bad username or password 550	Requested action not taken: mailbox unavailable 551	User not local; please try  552	Requested mail action aborted: exceeded storage allocation 553	Requested action not taken: mailbox name not allowed 554	Transaction failed