Attaching multiple MimeBodyParts to MimeMultipart but content is wrong

Question

Hi,
The code builds two attachments which each contains different data. It's billing information for two different populations sent as a single email message to accounting. The problem is that both mime parts end up with the content of whichever part was added last. This is the code that builds the mime parts:
                    // Build student data attachment
                    InputStream _isStudent = new ByteArrayInputStream(studentData.getBytes());
                    BinaryDataSource bdataStudent = new BinaryDataSource(_isStudent);
                    DataHandler dhStudent = new DataHandler(bdataStudent);
                    MimeBodyPart b3 = new MimeBodyPart();
                    b3.setContentID("text/plain");
                    b3.setDataHandler(dhStudent);
                    b3.setFileName("students.txt");
                    b3.addHeader("Content-Transfer-Encoding", "base64");
                    mp.addBodyPart(b3);
                    // Build employee data attachment
                    InputStream _isEmployee = new ByteArrayInputStream(employeeData.getBytes());
                    BinaryDataSource bdataEmployee = new BinaryDataSource(_isEmployee);
                    DataHandler dhEmpl = new DataHandler(bdataEmployee);
                    MimeBodyPart b2 = new MimeBodyPart();
                    b2.setContentID("text/plain");
                    b2.setDataHandler(dhEmpl);
                    b2.setFileName("employees.txt");
                    b2.addHeader("Content-Transfer-Encoding", "base64");
                    mp.addBodyPart(b2);
In this order, both parts contain the employee data. If I swap them around, both parts will contain student data. Filename information is correct and the problem seems to be exclusively with the data handler.
The odd thing is that this code hasn't been changed and now it's suddenly not working. Nor has the JavaMail jarfile been changed. It's an older version so I downloaded and tried the latest and greatest 1.4.4 release. I didn't think that would make a difference, and it didn't.
Any ideas about what could be going on here?
Thanks,
Rob Tanner
Linfield College

Answer 1

I don't see anything obviously wrong with your code so my guess is that
one of your assumptions is wrong, e.g.,
1. That's not really the code that's running.
2. You're not really using the JavaMail jar file that you think you're using
(perhaps you're getting the Gnu version by accident?)
3. BinaryDataSource isn't working correctly. You might try replacing BinaryDataSource
with ByteArrayDataSource from JavaMail.