SMTP 答复代码含义

500 Syntax error, command unrecognized. [This may include errors such as command line too long]
500 语法错误，命令无法识别。[这种错误可能包括命令行太长等]

501 Syntax error in parameters or arguments
501 语法错误在参数或论据

502 Command not implemented
502 命令不能执行

503 Bad sequence of commands
503 错误的命令次序

504 Command parameter not implemented
504 命令参数不能执行

211 System status, or system help reply
211 系统状态或系统帮助回复

214 Help message
214 帮助信息

220 Service ready
220 服务准备

221 Service closing transmission channel
221 服务关闭传输频道

421 Service not available, closing transmission channel.[This may be a reply to any command if the service knows it must shut down]
421 服务不可用，关闭传输频道。服务器即将关闭的信息

250 Requested mail action okay, completed
250 被请求的邮件完全准备好

251 User not local; will forward to
251 非本地用户，继续解析

450 Requested mail action not taken: mailbox unavailable.[E.g., mailbox busy]
450 邮箱无法使用。 [邮箱忙]

550 Requested action not taken: mailbox unavailable.[E.g., mailbox not found, no access]
550 邮箱无法使用。 [邮箱未找到，无法进入]

451 Requested action aborted: error in processing
451 错误处理

551 User not local; please try.
551 用户不在本地，请重试。

452 Requested action not taken: insufficient system storage
452 不足系统存储

552 Requested mail action aborted: exceeded storage allocation
552 超出存储分配

553 Requested action not taken: mailbox name not allowed.[E.g., mailbox syntax incorrect]
553 邮箱名称不允许的。[邮箱的格式不正确]

354 Start mail input; end with.
354 开始邮件输入;结束。

554 Transaction failed.
554 交易失败。