add mail.jar and activation.jar in ANT_HOME/lib or use both jar form your project/lib

问题描述：

   ant执行发送email的功能时报错：java.lang.ClassNotFoundException: javax.mail.internet.MimeMessage

解决办法：

  将mail.jar and activation.jar放到ant的lib下

转自：http://stackoverflow.com/questions/17302832/getting-error-message-java-lang-classnotfoundexception-javax-mail-internet-mim

Getting error message “java.lang.ClassNotFoundException: javax.mail.internet.MimeMessage” while executing ant mail task