Well, The Elastic Email rather than sending emails to your customers from your own SMTP , they have solution for your needs. They provide plug and play integration.

It sends an automated response with little to no configuration needed.

Elastic Email stands out for its exceptional deliverability rates, ensuring that our emails reach the intended audience's inboxes. The platform offers a comprehensive set of features that cater to the needs of marketing professionals, making it a powerful tool for creating and managing successful email campaigns. It's so easy to use and setup also. Customer service has helped me to setup it.