I use Sendgrid API for transactional emails and Mailchip Api for newsletters. If you mean to send transactional API, I would suggest Sendgrid. It offers easy to

I use Sendgrid API for transactional emails and Mailchip Api for newsletters. If you mean to send transactional API, I would suggest Sendgrid. It offers easy to implement APIs and gives you an option to categorize your transactional emails which can help you a lot in analytics.