Unable to send mails using NodeMailer

I am developing a MEAN Stack app in which I am trying to send mails through NodeMailer. I am able to send mails on local server but unable to send mails when I deployed my app on Heroku for testing. I am using https://webmail.domeneshop.no/ SMTP server.
NodeMailer returns the following error: "550-sender IP address 18.209.107.169 is part of Amazon AWS, and may not use 550-this server as a smarthost. Amazon servers should use Amazon SES 550 (https://aws.amazon.com/ses/)"