At javax.mail.transport.send0 transport.java 190

A JavaMail error!

The error message at javax.mail.transport.send0 transport.java 190 suggests that there's an issue with the JavaMail API's Transport class, specifically with the send() method.

Here are a few possible causes and solutions:

1. Invalid email address or recipient: Check that the email address or recipient you're trying to send to is valid and exists. Make sure you're not trying to send to a non-existent email address.
2. Network connectivity issues: Ensure that your network connection is stable and working properly. Try sending the email again after restarting your network connection or checking your internet connection.
3. SMTP server issues: Verify that your SMTP server is configured correctly and is reachable. You can try using a different SMTP server or checking the server's logs for any errors.
4. JavaMail configuration issues: Double-check your JavaMail configuration, including the SMTP host, port, username, and password. Make sure they're correct and match your email provider's settings.
5. Email content issues: Check the email content for any issues, such as invalid characters, attachments, or formatting. Try sending a simple text email to see if the issue persists.

To troubleshoot further, you can try the following:

• Enable JavaMail debugging to get more detailed error messages. You can do this by setting the mail.debug property to true before sending the email.
• Check the JavaMail API documentation for any specific requirements or limitations for the send() method.
• Search for similar issues online or in JavaMail forums to see if others have encountered similar problems.

If none of these solutions work, please provide more context or code snippets, and I'll do my best to help you troubleshoot the issue!