Disclaimer: happy customer of both SendGrid and MailChimp.
The risk of one of the Borg companies doing this to you at any time is yet another reason why you should not attempt to compete on price, and relatedly why you should probably not seek the business of equisitvely price sensitive customers.
To be fair, the price isn't just slightly lower - it is nearly an order of magnitude lower. Sending 500k messages a month with Amazon is $50, and with SendGrid it's $400.
If you send that level of email a month (which is easy to do if you send a weekly newsletter to a few hundred thousand users) you're now talking about saving yourself a few grand a year with Amazon.
Given the "switch" can be as simple as changing some SMTP settings, this is a big deal. I don't think the people who jump ship are necessarily hyper-price-sensitive customers. Amazon is just turning this service into a commodity.
You raise a great point. I'd really appreciate a little more input on the inboxing side of the deal though. We could say that SendGrid has that going for it, so I'm wondering if there's something we can do about that.
The risk of one of the Borg companies doing this to you at any time is yet another reason why you should not attempt to compete on price, and relatedly why you should probably not seek the business of equisitvely price sensitive customers.