https://news.ycombinator.com/item?id=11170713
I'll never trust them or use them again, after that. No way no how.
I've had extremely negative experiences in their customer support, but also extremely positive experiences through their community engagement as I'm local to them.
But they fucked over more than the free tier. We (work) had 15 clients that all had accounts that we managed for them. We probably spent upwards of $1200/mo on emails through those accounts.
We only got ~50 days of notice that we had to change over to another provider before we would get cut off.
Switching e-mail providers is not something you can do overnight if you send large volumes (large volume does not mean spam: I send purchase receipts, contact forms, notifications, password resets -- transactional mail not ads). Even if you have a team of coders that can drop everything to start integrating alternatives, you need time to warm up your new IP space at a new provider, or your mail ends up in spam folders.
MailChimp screwed a lot of customers, and customers' customers when they gave only 60 days notice.
Customers I know who were ultimately stuck by being heavily integrated in the Mandrill API still suffered issues and downtime with the flawed account migration process. Just about every paying (and non paying) Mandrill customer got screwed in one way or another.
We then switched to Amazon SES but still have a bitter feeling about MailChimp and will move our services that are using the full MailChimp product. Some of the change was indeed to control spammers, but when you are forcing over enterprises sending 100's of thousands of emails without complaint, that starts crossing the line where you want to better monetize your product. Giving your customers 60 days to engineer a different solution after they invested in your product is not good business.