我们在发邮件时候，经常会收到一些报错代码，小编整理了一些常见的报错，供参考：
>>553 host denies the sender. (拒绝发件人地址)\r\n
>>553 private list access denied. (列表访问拒绝)\r\n
>>553 relay check domain fail\r\n
>>553 relay check local fail. (本域用户必须通过验证)\r\n
>>552 message rejected by anti-spam engine.
>>553 fake router infomation.
>>554 Black mail address.
>>552 too many same size mails. (发送过多长度类似信件)\r\n
>>451 out of allow RCPT numbers. (超出 RCPT 允许上限)\r\n
>>450 out of memory. (内部错误)\r\n
>>551 auth error. (认证永久失败)\r\n
>>451 auth error. (认证临时失败)\r\n
>>451 domain auth support error\r\n
>>451 auth mode unsupported. (不支持的认证模式))\r\n
>>501 please say HELO/EHLO first\r\n
>>502 please say MAIL first\r\n
>>503 please say RCPT first\r\n
>>500 sequence error\r\n
>>500 syntax error\r\n
>>450 queue unavailable. (队列忙)\r\n
>>553 host denies relay. (拒绝中继)\r\n
>>552 mail from invalid. (发件人地址不合法)\r\n
>>552 looping message. (环回信件)\r\n
>>552 message is too long. (邮件大小超过限制)\r\n
>>554 attachment is too long. (单个附件大小超出限制)\r\n
>>554 sender is unvalidated. (发信人地址不合法)\r\n
>>450 mailbox unavailable. (邮箱暂时不可用)\r\n
>>550 mailbox unavailable. (邮箱不存在)\r\n
>>552 Virus found. (信件包含无法清除的病毒)\r\n
>>554 mail address invalid. (发件人地址不匹配)\r\n
>>556 remote ip check error. (发信ip与Mail From地址不一致)\r\n
>>555 helohost error.(helo 主机信息检查失败)\r\n
>>551 line parse error(该行违背协议).\r\n
>>550 user is locked. (邮箱被锁)\r\n
>>450 database temporary error. (临时数据访问失败)\r\n
>>554 smtpport check error. (不是合法的邮件服务器)\r\n
>>554 rbl deny. (拒绝 RBL 中的邮件服务器)\r\n
>>554 openrelay check. (拒绝开放中继服务器)\r\n
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