Holy shit. There goes any reluctance I had to building on top of SES. Your move, Sendgrid.

For what its worth, doesn't appear to be as easy as SendGrid, in that they only require SMTP settings.

I appreciate the transparency of this post.

This is quite a day for news from MailChimp. We had already decided to go with MailChimp for our bulk email needs and have been on the fence about Amazon SES vs SendGrid. But with us already leaning toward Amazon SES, this pretty much just seals the deal.

The real value of this is in the integration of unsubscribe lists and reporting on opens, CTRs, bounce rates etc... well played!

Can you use mailchimp to send dynamic emails with their API? For example, from a PHP script when a new user joins your site?

That is precisely what they've launched on top of SES.

Yes, using their pseudo-transactional campaigns. I'm using it right now on multiple sites. Which makes me wonder why they decided to build on SES, they've already got the functionality there...

http://blog.mailchimp.com/transactional-email-support/

Probably because they were pseudo-transactional.

Copying this from my blog comment answering the same question...

Pseudo-transactional campaigns are very "pseudo". MailChimp campaigns require static predefined content. If you actually wanted to vary the content from recipient to recipient, you need to find a way to stuff the dynamic content into merge fields as you send which can cause latency and concurrency issues.

Also, since pseudo-transactional campaigns uses our sending infrastructure tuned for large bulk mailing, the delivery times are somewhat longer (on the order of minutes) for pseudo-transactional campaigns, vs seconds for STS.

Building atop your competitors. Nice tactic.