Question: what are the main benefits of using an email service provider?
Answer: Email volume. Email Service Providers are built to handle large volume email sends both in terms of size and speed. ... 
List management and personalization. ... 
Email tracking. ... 
Subscriber management. ... 
Separation of marketing emails. ... 
Effective HTML design. ... 
Enforcement of CAN-SPAM and other email regulations. ... 
Campaign automation.