Couldn't connect to host, port: smtp.alibaba.com, 25错误解决办法-优快云博客

本文详细解析了在使用JavaMail进行邮件发送时遇到的SMTP连接超时错误，包括异常堆栈跟踪及解决方案。通过调整邮件服务器端口从25到465，并启用SSL加密，成功解决了连接失败的问题。

com.sun.mail.util.MailConnectException: Couldn't connect to host, port: smtp.alibaba.com, 25; timeout -1;
nested exception is:
   java.net.ConnectException: Connection timed out (Connection timed out)
   at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:2118)
   at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:712)
   at javax.mail.Service.connect(Service.java:366)
   at javax.mail.Service.connect(Service.java:246)
   at javax.mail.Service.connect(Service.java:267)
   at com.ej.common.support.email.MailSender$1.run(MailSender.java:132)
   at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
   at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
   at java.lang.Thread.run(Thread.java:748)
Caused by: java.net.ConnectException: Connection timed out (Connection timed out)
   at java.net.PlainSocketImpl.socketConnect(Native Method)
   at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
   at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
   at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
   at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
   at java.net.Socket.connect(Socket.java:589)
   at java.net.Socket.connect(Socket.java:538)
   at com.sun.mail.util.SocketFetcher.createSocket(SocketFetcher.java:331)
   at com.sun.mail.util.SocketFetcher.getSocket(SocketFetcher.java:238)
   at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:2084)
   ... 8 more

把mail.smtp.port端口号由25改为465

props.put("mail.smtp.port", "25");

，并加上，不加会出现Could not connect to SMTP host: smtp.gdyilian.com, port: 465

props.put("mail.smtp.ssl.enable", "true");