Website Standard and Pro uses SendGrid which delivers your transactional and marketing emails through the world's largest cloud-based email delivery platform. Based on your preferences you can either use the inbuilt mail system or can opt for another external email system based on the plugin setup.
The external SMTP plugin ,WP Mail SMTP should work fine on our hosting. In case you were to use these plugins, you need to disable the Website Pro's inbuilt sendgrid mail system.
Steps to follow: Navigate to Wordpress Dashboard > Settings > General > Disable Website Pro Mail System > Save changes once done.
This option needs to be disabled only when you want to use your own email delivery system. 