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使用Java的电子邮件通知我可能会遇到错误，因为无法连接到SMTP主机：RELAY.MY.COM，端口：25，响应：421

[英]Email notification using java i can face error as Could not connect to SMTP host: RELAY.MY.COM, port: 25, response: 421

原文 2014-06-20 15:34:00 8 1 java/ java-ee/ struct

在此处输入图片说明 This error is occurring occasionally and i couldn't find the root cause of this issue. 偶尔会发生此错误，而我找不到此问题的根本原因。 plz help me out of this issue. 请帮我解决这个问题。

1 个解决方案

SMTP Status Codes SMTP状态码

4.2.1 4.2.1

The Mail transfer service is unavailable because of a transient event. 由于发生临时事件，邮件传输服务不可用。 SMTP reply SMTP回复

421 can be caused by many things but generally indicates that the mail server which returns this status code is currently unavailable but may be available later. 421可能是由许多原因引起的，但通常表示返回此状态代码的邮件服务器当前不可用，但以后可能可用。

For example, the server administrator may have stopped the mail service to troubleshoot a problem, or the mail server is right in the middle of rebooting, or the mail server is currently processing too many incoming messages or incoming requests, etc... Note : “Mail Server” in this case can be any of the mail servers on the message's route – the sending server (your server), the ISP SMTP server, or the recipient's mail server. 例如，服务器管理员可能已停止邮件服务以解决问题，或者邮件服务器正处于重新启动过程中，或者邮件服务器当前正在处理过多的传入消息或传入请求等。注意：在这种情况下，“邮件服务器”可以是邮件路径上的任何邮件服务器-发送服务器（您的服务器），ISP SMTP服务器或收件人的邮件服务器。

Clearly, if you repeatedly receive an SMTP status 421 then the problem is no longer of a transient nature and you need to investigate or inform the relevant network administrator, ISP tech support, or the recipient. 显然，如果您反复收到SMTP状态421，则问题不再是暂时性的，您需要调查或通知相关的网络管理员，ISP技术支持或收件人。

SMTP Response 421 can also be received as a result of your message server sending an email where the total number of TO, CC, and BCC users results in a number of simultaneous SMTP connections that is in excess of the number of connections your ISP or SMTP service allows. 邮件服务器发送电子邮件后，也可能会收到SMTP响应421，其中TO，CC和BCC用户的总数导致同时SMTP连接数超过了ISP或SMTP的连接数服务允许。 A typical error message for this situation would be : “421 Too many concurrent SMTP connections from this IP address; 对于这种情况，典型的错误消息将是：“ 421该IP地址的并发SMTP连接过多； please try again later”. 请稍后再试”。 Typically, when this happens your server will have sent some of the messages (note that for all servers, each email sent by a user always gets broken down into individual separate emails to each of the recipients in the TO, CC, and BC fields), and will automatically retry a little later to send the remaining messages. 通常，发生这种情况时，您的服务器将发送一些消息（请注意，对于所有服务器，用户发送的每封电子邮件始终会分解为单独的电子邮件，分别发送给TO，CC和BC字段中的每个收件人），稍后会自动重试以发送剩余的消息。