We split transactional emails between Mandrill App (Mailchimp's transactional service) and Amazon SES for now. Never had an issue with either one, but I built

We split transactional emails between Mandrill App (Mailchimp's transactional service) and Amazon SES for now. Never had an issue with either one, but I built the dual solution because of concerns about having an email get one line shut off. Also, for our newsletter, we use Mailchimp and not either transactional service. When we were researching who to use Sendgrid was in the top few but my research showed they were less transparent about almost everything, which pushed us towards our current solution.