配置jenkins邮箱测试报错：
java.net.SocketException: Connection closed by remote host
at sun.security.ssl.SSLSocketImpl.checkWrite(SSLSocketImpl.java:1565)
at sun.security.ssl.AppOutputStream.write(AppOutputStream.java:71)
at com.sun.mail.util.TraceOutputStream.write(TraceOutputStream.java:114)
at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)
at com.sun.mail.smtp.SMTPTransport.sendCommand(SMTPTransport.java:2104)
Caused: javax.mail.MessagingException: Can’t send command to SMTP host;
nested exception is:
java.net.SocketException: Connection closed by remote host
at com.sun.mail.smtp.SMTPTransport.sendCommand(SMTPTransport.java:2106)
at com.sun.mail.smtp.SMTPTransport.sendCommand(SMTPTransport.java:2093)
at com.sun.mail.smtp.SMTPTransport.issueCommand(SMTPTransport.java:2017)
at com.sun.mail.smtp.SMTPTransport.helo(SMTPTransport.java:1440)
at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:644)
解决方案：
将使用ssl协议切换成TLS协议
