Mandrill, MailChimp’s SMTP-as-a-service offering with 800,000 customers and a $12MM ARR is essentially shutting down. They’re merging it into MailChimp, but updated the TOS and AUP with immediate effect in ways that essentially banned what was the service’s raison d’être: sending bulk mail programmatically.
You can no longer use it to send mail on behalf of your users, as in a contact form processor or white labeled service. You can no longer use it to send the same mail to multiple people, like an alert or notification. So, for many many businesses that relied on it, the rug’s been pulled out from under us with essentially no notice.
Send bulk emails, meaning emails directed to a number of individuals with the same content, through Mandrill.
— Acceptable Use Policy
There’s a whole post about the philosophy behind merging Mandrill and MailChimp on their blog, but no explanation for why there was not even a day of notice regarding the AUP changes. What a way to treat your customers.