MessagingException thrown on some machines, but on others it works fine - jakarta-mail

Question

I'm trying to write a method that sends an email based on parameters, and it works completely on CentOS and OSX. However, the method doesn't work properly on Windows (even when recompiled on Windows) as well as some other Linux OS's - it throws a MessagingException. Does anyone have any ideas as to how I can fix this to work on Windows? Thanks!
private static void sendEmail(String towhom, String subject, String body) {
String host = "smtp.gmail.com", from = "myemail", pass = "mypassword";
Properties props = System.getProperties();
Scanner scan = new Scanner(System.in);
try {
props.put("mail.smtp.starttls.enable", "true");
props.put("mail.smtp.host", host);
props.put("mail.smtp.user", from);
props.put("mail.smtp.password", pass);
props.put("mail.smtp.port", "587");
props.put("mail.smtp.auth", "true");
Session session = Session.getDefaultInstance(props, null);
MimeMessage message = new MimeMessage(session);
message.setFrom(new InternetAddress(from));
InternetAddress toAddress = new InternetAddress(towhom);
message.addRecipient(Message.RecipientType.TO, toAddress);
message.setSubject(subject);
message.setText(body);
Transport transport = session.getTransport("smtp");
transport.connect(host, from, pass);
transport.sendMessage(message, message.getAllRecipients());
transport.close();
}
catch(AddressException e) {
System.out.println("Invalid Email Address.");
}
catch(MessagingException e) {
System.out.print("\nInvalid Email Address, please reenter it: ");
sendEmail(scan.nextLine(), subject, body);
}
}

Answer 1

So yes Avast Antivirus was causing the exception to be thrown when I was trying to send the mail. If anyone else has this problem who finds this page:
Open up Avast and click on the Security tab. Then click on the AntiVirus tab on the left. Under that, click Mail Shield and go to the settings. Untick "Scan outbound mail (SMTP)" and it will work like a charm.

Answer 2

There is no problem with your code. It looks good.
According to the JavaMail FAQ's. Following could be the problem -
There's a firewall or anti-virus program intercepting your request.
There's something wrong in your JDK installation preventing it from finding the certificates for the trusted certificate authorities.
You're running in an application server that has overridden the JDK's list of trusted certificate authorities.
If disabling your firewall and/or anti-virus does not solve the problem then you can try and reinstall the JDK and test.