我已经编写了一个小测试程序，尝试使用JavaMail发送邮件。我在Java中遇到了奇怪的行为，我不确定如何修复它。基本设置是我的测试程序是从仅支持IPv6的Linux盒子运行的，但是它正试图发送到IPv4＆amp;双栈环境中的IPv6 SMTP服务器。我的意思是双栈环境是DNS服务器有一个A和AAAA记录与smtp服务器的主机名相同，据我所知这应该是合法的。当我用A和AAAA记录运行我的程序时，我得到以下异常：
javax.mail.MessagingException: Could not connect to SMTP host: <MY Fully qualified domain name>, port: 25;
nested exception is:
java.net.SocketException: Network is unreachable
at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1282)
at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:370)
at javax.mail.Service.connect(Service.java:275)
at javax.mail.Service.connect(Service.java:156)
at javax.mail.Service.connect(Service.java:105)
at javax.mail.Transport.send0(Transport.java:168)
at javax.mail.Transport.send(Transport.java:98)
Caused by: java.net.SocketException: Network is unreachable
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at com.sun.mail.util.SocketFetcher.createSocket(SocketFetcher.java:232)
at com.sun.mail.util.SocketFetcher.getSocket(SocketFetcher.java:189)
at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1250)
... 8 more
但是，如果我删除A记录，那么我可以毫无问题地访问SMTP服务器。无论我给出什么值，我都会给java属性＆＃39; java.net.preferIPv6Addresses＆＃39; ＆＃39; java.net.preferIPv4Stack＆＃39;只有AAAA记录时，程序才能访问smtp服务器。如果同一主机名的A和AAAA记录都存在，我如何告诉Java使用AAAA记录并防止它获得套接字异常？