void error(Throwable ex) {
    if (ex instanceof MessagingException &&
            ("connection failure".equals(ex.getMessage()) ||
                    "Not connected".equals(ex.getMessage()) || // POP3
                    ex.getCause() instanceof SocketException ||
                    ex.getCause() instanceof ConnectionException))
        recoverable = false;

    if (ex instanceof ConnectionException)
        // failed to create new store connection
        // BYE, Socket is closed
        recoverable = false;

    if (ex instanceof StoreClosedException ||
            ex instanceof FolderClosedException ||
            ex instanceof FolderNotFoundException)
        // Lost folder connection to server
        recoverable = false;

    if (ex instanceof IllegalStateException && (
            "Not connected".equals(ex.getMessage()) ||
                    "This operation is not allowed on a closed folder".equals(ex.getMessage())))
        recoverable = false;

    if (ex instanceof OperationCanceledException)
        recoverable = false;

    thread.interrupt();
    yield();
}
 

static String formatThrowable(Throwable ex, String separator, boolean sanitize) {
    if (sanitize) {
        if (ex instanceof MessageRemovedException)
            return null;

        if (ex instanceof AuthenticationFailedException &&
                ex.getCause() instanceof SocketException)
            return null;

        if (ex instanceof MessagingException &&
                ("connection failure".equals(ex.getMessage()) ||
                        "failed to create new store connection".equals(ex.getMessage())))
            return null;

        if (ex instanceof MessagingException &&
                ex.getCause() instanceof ConnectionException &&
                ex.getCause().getMessage() != null &&
                (ex.getCause().getMessage().contains("Read error") ||
                        ex.getCause().getMessage().contains("Write error") ||
                        ex.getCause().getMessage().contains("Unexpected end of ZLIB input stream") ||
                        ex.getCause().getMessage().contains("Socket is closed")))
            return null;

        // javax.mail.MessagingException: AU3 BAD User is authenticated but not connected.;
        //   nested exception is:
        //  com.sun.mail.iap.BadCommandException: AU3 BAD User is authenticated but not connected.
        // javax.mail.MessagingException: AU3 BAD User is authenticated but not connected.;
        //   nested exception is:
        // 	com.sun.mail.iap.BadCommandException: AU3 BAD User is authenticated but not connected.
        // 	at com.sun.mail.imap.IMAPFolder.logoutAndThrow(SourceFile:1156)
        // 	at com.sun.mail.imap.IMAPFolder.open(SourceFile:1063)
        // 	at com.sun.mail.imap.IMAPFolder.open(SourceFile:977)
        // 	at eu.faircode.email.ServiceSynchronize.monitorAccount(SourceFile:890)
        // 	at eu.faircode.email.ServiceSynchronize.access$1500(SourceFile:85)
        // 	at eu.faircode.email.ServiceSynchronize$7$1.run(SourceFile:627)
        // 	at java.lang.Thread.run(Thread.java:764)
        // Caused by: com.sun.mail.iap.BadCommandException: AU3 BAD User is authenticated but not connected.
        // 	at com.sun.mail.iap.Protocol.handleResult(SourceFile:415)
        // 	at com.sun.mail.imap.protocol.IMAPProtocol.select(SourceFile:1230)
        // 	at com.sun.mail.imap.IMAPFolder.open(SourceFile:1034)

        if (ex instanceof MessagingException &&
                ex.getCause() instanceof BadCommandException &&
                ex.getCause().getMessage() != null &&
                ex.getCause().getMessage().contains("User is authenticated but not connected"))
            return null;

        if (ex instanceof IOException &&
                ex.getCause() instanceof MessageRemovedException)
            return null;

        if (ex instanceof ConnectionException)
            return null;

        if (ex instanceof StoreClosedException ||
                ex instanceof FolderClosedException || ex instanceof FolderClosedIOException)
            return null;

        if (ex instanceof IllegalStateException &&
                ("Not connected".equals(ex.getMessage()) ||
                        "This operation is not allowed on a closed folder".equals(ex.getMessage())))
            return null;
    }

    StringBuilder sb = new StringBuilder();
    if (BuildConfig.DEBUG)
        sb.append(ex.toString());
    else
        sb.append(ex.getMessage() == null ? ex.getClass().getName() : ex.getMessage());

    Throwable cause = ex.getCause();
    while (cause != null) {
        if (BuildConfig.DEBUG)
            sb.append(separator).append(cause.toString());
        else
            sb.append(separator).append(cause.getMessage() == null ? cause.getClass().getName() : cause.getMessage());
        cause = cause.getCause();
    }

    return sb.toString();
}
 

protected synchronized void checkOpened() throws FolderClosedException {

        if (!opened) {

            throw new IllegalStateException("This operation is not allowed on a closed folder " + objectId);

        }
    }
 

@Override
protected void checkOpened() throws FolderClosedException {

    if (!opened) {

        throw new IllegalStateException("This operation is not allowed on a closed folder: " + getFullName() + " (" + objectId + ")");

    }
}