Mailchimp’s transactional email service has long been the go-to engine for reliable, event-triggered communication, whether developers came to know it as Mailchimp Transactional or by its former name, Mandrill[1]. Mailchimp’s infrastructure sends up to 157 billion emails per month, and Mailchimp Transactional has gained a reputation as a scalable platform that can handle any volume a business demands, from startup to enterprise. Our users know they can count on a strong foundation of 99.99% uptime, an average email delivery rate of over 99%, and a fast median delivery speed of less than 1 second to customers’ inboxes.
But while this mission-critical tool has endured as a reliable, consistent center for one-to-one customer updates, we’ve been monitoring your feedback about how we can modernize the platform without changing the functionality you rely on. As an engineer myself, it’s a balance I understand: Your workflow needs to be as efficient and consistent as possible, even as certain components evolve or improve. Today, we’re proud to announce a massive improvement in the core developer experience for Mailchimp Transactional, and share some of the exciting optimizations and additions to the product that you can expect in the coming months.
First, we’ve given the Mailchimp Transactional UI a complete refresh. We’ve modernized the Transactional interface to reflect the modernized experience offered across Mailchimp’s other core marketing tools. We see this investment as a crucial step toward a seamless marketer-developer collaboration space. We’ve also enhanced our documentation. We know that clear guidance is critical for faster integration, so we’ve updated parts of our API docs to include more real-world code samples in major languages, and improved our onboarding guides to help you get to your first API call faster.
Our new API documentation also follows OpenAPI standards, making it easier to integrate our tools into your existing workflows. This approach provides a clear, consistent contract for our API, enabling you to quickly build with confidence.
But this is just the beginning. We’re also excited to announce that we’ve added new channel, Transactional SMS[2], which allows businesses to send non-promotional, one-to-one text messages triggered by specific customer actions or events, complementing the existing transactional email product. Now available in 10+ countries—the United States, Canada, Australia, United Kingdom, Germany, Austria, Switzerland, the Netherlands, France, Spain, and Ireland.
With this release, you’ll be able to see your transactional SMS messages right from your Transactional dashboard, providing a unified view of your omnichannel communications and further solidifying Mailchimp Transactional’s place as Mailchimp’s vital engine for event-triggered messaging. The new Mailchimp Transactional SMS capability leverages Mailchimp’s existing infrastructure and expertise in deliverability to help with compliance and ensure that critical messages reach the intended recipients effectively. This development is just the latest development in Mailchimp’s strategy to invest in and improve its transactional services, building upon the foundation of Mailchimp Transactional.
We’ll be also hosting live virtual office hours for developers on Nov 12, 2025 to share more on what’s new with Mailchimp Transactional, get into details on API parameters, and answer your questions. Register here to attend the Mailchimp Transactional Developer office hours. For questions in the meantime, contact us here.
By prioritizing a best-in-class developer experience today, we’re laying the groundwork to help free up engineering time for mission-critical work while giving marketers the control they need to move fast. Stay tuned for more details and updates in the transactional space in the coming months.
- Transactional Email is available as an add-on to Standard and Premium plans, or the legacy Monthly Plan. Pricing varies.
- Features and functionality vary by plan and certain features may have limited availability. Transactional SMS is available in select countries for Mailchimp users with active SMS and Transactional Email (Mandrill) plans. Availability is subject to change. See Mailchimp.com for details.