Open javamail folder failed

Question

I developed an email website using javamail and apache-james and it works well mostly. But some user got Open failed Exception and cannot receive new mail. The code of receive email:

Session mailSession = Session.getInstance(System.getProperties(), null);
mailSession.setDebug(false);
Store store = null;
Folder folder = null; //javax.mail.Folder
try {
    store = mailSession.getStore(SParam.PROTOCOL);
    store.connect(Property.getPop3(), userName, password);
    logger.info("trying to receive emails from james server...");
    folder = store.getFolder("INBOX");
    try {
        if (!folder.isOpen()) {
            folder.open(Folder.READ_WRITE); //the point of throwing the exception
        }
    } catch (Exception e) {
        // TODO: handle exception
        e.printStackTrace();
    }
    //receive email from james server.
} catch (Exception e) {
    logger.error("Email Receive Error!" + StackTraceStr.st2str(e));
    try {
        folder.close(true);
    } catch (Exception e2) {
}
} finally {
    try {
        store.close();
    } catch (Exception cloex) {
    }
}

In most cases, it works just fine. But still got the error occasionally:

javax.mail.MessagingException: Open failed;
nested exception is:
java.io.IOException: STAT command failed: null
at com.sun.mail.pop3.POP3Folder.open(POP3Folder.java:228)
at com.csc.mail.jsh.mail.core.ReceiveMail.receive(ReceiveMail.java:82)
at com.csc.mail.jsh.mail.core.ReceiveMail.run(ReceiveMail.java:222)
at java.lang.Thread.run(Thread.java:619)
Caused by: java.io.IOException: STAT command failed: null
at com.sun.mail.pop3.Protocol.stat(Protocol.java:366)
at com.sun.mail.pop3.POP3Folder.open(POP3Folder.java:203)
... 3 more

Waiting your help and thanks a lot!

I debug and debug, finally found the STAT command failed! when STAT command got an error, there's an exception of james, but that makes no sence!

21/11/12 14:39:16 ERROR pop3server: Exception during connection from 127.0.0.1     
    (127.0.0.1) : An exception occurred getting a database connection.
    org.apache.avalon.framework.CascadingRuntimeException: An exception occurred getting a database connection.
at org.apache.james.userrepository.AbstractJdbcUsersRepository.openConnection(AbstractJdbcUsersRepository.java:617)
    at org.apache.james.userrepository.AbstractJdbcUsersRepository.getUserByName(AbstractJdbcUsersRepository.java:521)
    at org.apache.james.userrepository.AbstractUsersRepository.test(AbstractUsersRepository.java:270)
    at org.apache.james.core.LocalUsersRepository.test(LocalUsersRepository.java:90)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.apache.avalon.phoenix.components.application.BlockInvocationHandler.invoke(BlockInvocationHandler.java:134)
    at $Proxy4.test(Unknown Source)
    at org.apache.james.pop3server.POP3Handler.doPASS(POP3Handler.java:537)
    at org.apache.james.pop3server.POP3Handler.parseCommand(POP3Handler.java:479)
    at org.apache.james.pop3server.POP3Handler.handleConnection(POP3Handler.java:277)
    at org.apache.james.util.connection.ServerConnection$ClientConnectionRunner.run(ServerConnection.java:432)
    at org.apache.excalibur.thread.impl.ExecutableRunnable.execute(ExecutableRunnable.java:55)
    at org.apache.excalibur.thread.impl.WorkerThread.run(WorkerThread.java:116)
Caused by: java.sql.SQLException: Listener refused the connection with the following error:
    ORA-12519, TNS:no appropriate service handler found
    The Connection descriptor used by the client was: 192.168.250.23:1521:csmis
    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:112)
    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:261)
    at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:387)
    at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:439)
    at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:165)
    at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:35)
    at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:801)
    at org.apache.commons.dbcp.DriverConnectionFactory.createConnection(DriverConnectionFactory.java:37)
    at org.apache.commons.dbcp.PoolableConnectionFactory.makeObject(PoolableConnectionFactory.java:290)
    at org.apache.commons.pool.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:771)
    at org.apache.commons.dbcp.PoolingDataSource.getConnection(PoolingDataSource.java:95)
    at org.apache.commons.dbcp.BasicDataSource.getConnection(BasicDataSource.java:540)
    at org.apache.james.util.dbcp.JdbcDataSource.getConnection(JdbcDataSource.java:220)
    at org.apache.james.userrepository.AbstractJdbcUsersRepository.openConnection(AbstractJdbcUsersRepository.java:614)
... 15 more

All application runs on the same server, and there's only a few users online(when I test it, only me use it). The error just appear occasionally. Why?

Answer 1

I had contact with Apache James and finally found the answer. You can find it at here: STAT command failed occasionally. At the end of the page, the thread had been listed.

Answer 2

It seems to be a mail server issue. STAT command is used to show number of messages. Normally STAT is the first command to run after successfully connected to the mail server.

Try to use mailSession.setDebug(true) to enter debug mode to get more error logs.