Thanks @sarav_prakash , here we are using the AEM as a cloud service and there is a form for which we have used default.mailService and that is working fine on the environment as well but when we used the transport.send() from javax.mail it is not working.

We need to implement multiple forms on our site, each with a different server name and "from" address, but this setup is not working as expected. We're referencing the documentation from this link:https://joao.ws/how-to-send-custom-emails-in-aem-part-2-multiple-providers/.but this form is not workin...