[support] Subscription email scheduling

Hello, I am working on a Drupal 7 website. I have configured the subscription module for that Drupal 7 website. Now the Server on which website is hosted has limitation of 700 emails /hr. How we can schedule these subscription in the batch of 500/hr ? Is there any module available that supports the cron job / email scheduling with subscription module. Thanks in Advance ! -- Nikhil Kala