Jakarta Mail works as standalone but not in Web Applicaton - where it throws Authentication exception

Question

I have managed to write a Java Program successfully to generate an email from my GMail account to the outlook account. Here is the excerpt of the code:

String to="<my>@outlook.com";
        String from="<my>@gmail.com";
        final String username="<my>@gmail.com";
        final String password="<App pw genertaed at GMail>";
        String host="smtp.gmail.com";
        
        Properties prop =new Properties();
        prop.put("mail.smtp.host", host);
        prop.put("mail.smtp.auth", true);
        prop.put("mail.smtp.starttls.enable", true);
        prop.put("mail.smtp.port", "587");
        
        Authenticator authenticator = new Authenticator() {
            protected PasswordAuthentication getPasswordAuthentication(){
                return new PasswordAuthentication(username,password);
            }
        };
        
        Session session = Session.getDefaultInstance(prop, authenticator);
<skipped rest of the steps for brevity>

This code sends the email from my gmail to outlook successfully.
However, if I try to use the same code in my Web Application, the application throws the following exception:

jakarta.mail.SendFailedException: Send failure (jakarta.mail.MessagingException: Connection error (java.net.ConnectException: Connection refused))

All my Jakara Mail configuration is in the file webapp/META-INF/context.xml and the configuration is a below:

<Context path="/mywebapp">
    <Resource id="mail/webapp" type="jakarta.mail.Session">
        mail.smtp.host=smtp.gmail.com
        mail.smtp.port=587
        mail.transport.protocol=smtp
        mail.smtp.auth=true
        mail.smtp.user=<my>@gmail.com
        password=<App pw genertaed at GMail>
    <\/Resource>
<\/Context>

Since I am running the WebApp on Tomee9, the above config details are as the the Server's official documentation

I am completely confused, what wrong am I doing?

Any feedback would be appreciated. Many Thanks