What causes "MailConnection.Error.CountingAttachedFiles" in pentaho/pentaho-kettle?

Check the wrapped cause to see if it is an IO problem (connection) or MIME parsing problem

pentaho/pentaho-kettle · error · KettleException

MailConnection.Error.CountingAttachedFiles

Error message

MailConnection.Error.CountingAttachedFiles

What it means

Thrown while counting attachments of the current message: any Exception raised walking the message content (Part/Multipart traversal) is wrapped in a KettleException with this message including the message number. It indicates the message body could not be read or parsed.

Solutions

Check the wrapped cause to see if it is an IO problem (connection) or MIME parsing problem
Re-fetch the message or reopen the folder and retry
Skip messages with unparsable content by logging and continuing (set messages not downloaded / limit fields)
Update the mail server/Jakarta Mail version if a specific MIME structure fails

Example fix

// before
int count = connection.countAttachedFiles(); // throws on malformed message
// after
try {
  int count = connection.countAttachedFiles();
} catch ( KettleException e ) {
  logBasic( "Skipping message " + msgNum + ": " + e.getMessage() );
  count = 0;
}

Defensive patterns

Strategy: try-catch

Type guard

boolean isMultipart = ( data.message instanceof javax.mail.internet.MimeMessage )
  && ( (MimeMessage) data.message ).getContent() instanceof javax.mail.Multipart;

Try / catch

try {
  count = connection.countAttachedFiles();
} catch ( KettleException e ) {
  logBasic( "Attachment count failed for message #" + msgNum + ": " + e.getCause() );
  count = -1; // treat as unknown and continue
}

Prevention

Skip or quarantine messages with malformed MIME content
Keep the mail session connected while iterating messages
Test with problematic emails from the actual mailbox before production runs

When it happens

Trigger: Calling countAttachedFiles (attachment counting during MailInput processing) on a message whose content is not a Multipart, or whose content throws IOException/MessagingException when accessed (corrupt message, connection drop).

Common situations: Malformed or virus-scanner-quarantined messages; server connection lost while lazy-loading body parts; messages with unusual MIME structures.

Related errors

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/78835ea1f035c614. Report an issue: GitHub.

Appendix: source

Thrown at plugins/email-messages/impl/src/main/java/org/pentaho/di/job/entries/getpop/MailConnection.java:1653

          if ( ( disposition != null )
            && ( disposition.equalsIgnoreCase( Part.ATTACHMENT ) || disposition.equalsIgnoreCase( Part.INLINE ) ) ) {
            String MimeText = null;
            try {
              MimeText = MimeUtility.decodeText( part.getFileName() );
            } catch ( Exception e ) {
              // Ignore errors
            }
            if ( MimeText != null ) {
              String filename = MimeUtility.decodeText( part.getFileName() );
              if ( isWildcardMatch( filename, pattern ) ) {
                retval++;
              }
            }
          }
        }
      }
    } catch ( Exception e ) {
      throw new KettleException( BaseMessages.getString( PKG, "MailConnection.Error.CountingAttachedFiles", ""
        + this.message.getMessageNumber() ), e );
    } finally {
      if ( content != null ) {
        content = null;
      }
    }
    return retval;
  }

  private Message[] loadMboxMessages() throws KettleException {
    String mboxPath = getSourceMboxPath();
    File mboxFile = new File( mboxPath );

    if ( mboxFile.exists() && mboxFile.length() == 0 ) {
      return new Message[0];
    }

    mboxMessageNumbers.clear();

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