It might just help them. If Amazon just undercut their infrastructure costs, they can ditch their own servers and simply route mails through Amazon.

Regardless, MailChimp does a lot of stuff besides just sending mail. I suspect that most of its customers are there for the list management and campaign management pieces rather than just the .send() bit.

I haven't been managing our email messaging, but this seems considerably cheaper than Sendgrid which charges something exorbitant (I mean, its like $80 a month, but they're f*cking emails).

Does anyone have a perspective on whether their service is just as good?

I don't think it will kill off the likes of SendGrid. It might actually help expose Email-as-a-Service to potential customers who weren't aware that those companies existed. In the end it could expand the market for everyone and end up benefiting the competition as well.

Pick an Amazon Web Service and for most (all?) there are several standalone companies competing on quality, customer service, and ease of use.

The problem for the competition is that Amazon's suite of services is getting more and more comprehensive and using ALL of their offerings really does lower development overhead (versus picking and choosing the best standalone Email/Queue/Storage/CPU offering).