发送过程中的错误代码与错误信息对照表

512 "Unexpected SMTP Login response";
513 "Failed to get header of body part";
514 "Failed to get body of body part";
515 "Failed to ger footer of body part";
516 "Unexpected EHLO response";
517 "Unexpected HELO response";
518 "Unexpected QUIT response";
519 "Unexpected MAIL FROM response";
520 "Unexpected DATA response";
521 "Unexpected End of Message response";
522 "File too large to mail";
523 "Cannot mail 0 byte length file";
524 "Unexpected RCPT TO response";
525 "Unexpected AUTH LOGIN response";
526 "Unexpected AUTH LOGIN username request";
527 "Unexpected AUTH LOGIN username response";

528 "Unexpected AUTH LOGIN password request";
529 "Unexpected AUTH LOGIN password response";
530 "Unexpected AUTH PLAIN response";
531 "Unexpected AUTH PLAIN username request";
532 "Unexpected AUTH PLAIN username response";
533 "Unexpected AUTH PLAIN password request";
534 "Unexpected AUTH PLAIN password response";
535 "Unexpected CRAM-MD5 response";
536 "Unexpected CRAM-MD5 digest response";
537 "Failed to perform NTLM authentication";
538 "Unexpected AUTH NTLM response";
539 "Failed to base64 decode data";
540 "Failed to base64 encode data";
541 "Failed to create SSL socket";
542 "Failed to connect to Socks 4 proxy via SSL";
543 "Failed to connect to Socks 5 proxy via SSL";

544 "Failed to connect to HTTP proxy via SSL";
545 "Failed to connect via SSL";
546 "Failed to send data via SSL";
547 "Failed to receive data via SSL";