What This Integration Does
This integration uses Twilio as the SMS layer and Mailchimp as the email engine, with each acting on signals from the other. SMS opt-ins captured through Twilio add subscribers to the right Mailchimp audience with the source channel recorded. Inbound SMS messages (keywords, replies, two-way conversations) trigger Mailchimp email automations. And Mailchimp campaign events can fire follow-up SMS through Twilio for time-sensitive nudges.
It exists because text messages and email do different jobs well, and the best lifecycle programmes use both. That only holds true when the data flows cleanly between them.
The Workflow
When a customer texts a keyword like JOIN or OFFERS to a Twilio number, the integration receives the inbound webhook, captures the phone number, sends a double opt-in confirmation back through Twilio, and on confirmation adds the contact to the matching Mailchimp audience with the SMS keyword recorded as a tag. The Mailchimp welcome flow fires automatically, but only after the SMS double opt-in is confirmed, so compliance is enforced at the source.
A specific chain: a B2C retailer runs a “Text VIP to 12345” promotion. A customer texts in, receives the confirmation request, replies YES, and within seconds is in the “SMS VIP” audience in Mailchimp. The first welcome email lands minutes later with a member discount code. Three days later, if the customer has not used the code, Mailchimp fires a reminder email; if still unused after seven days, the integration sends a Twilio SMS reminder timed for late afternoon when SMS open rates are highest.
Inbound SMS to existing contacts route to the right place too. A customer replying STOP unsubscribes in both Twilio and Mailchimp simultaneously. A customer replying with a question that does not match a keyword routes to the customer service inbox with the Mailchimp profile attached so the agent has full context.
Before and After
Before, SMS and email are run as separate channels with no shared subscriber list. SMS opt-ins go to a spreadsheet or a Twilio dashboard. Email unsubscribes do not stop the SMS programme. Compliance is patchy.
After, the subscriber is one person across both channels. Opt-ins, opt-outs, and preferences flow through both. SMS triggers email; email triggers SMS; engagement on one updates segments on the other.
Who Needs This
Consumer brands, retailers, fitness businesses, and event-driven organisations that run both SMS and email and want the two to work as a single lifecycle programme. The integration is worth building when SMS volume is high enough that running it as a separate channel creates real compliance and consistency risks.
How We Build This
We build this against the Twilio Programmable Messaging API and the Mailchimp Marketing API. Twilio handles the SMS sending and receiving, with webhook subscriptions on inbound and status events. Mailchimp handles email and audience segmentation. Our integration sits between them, enforcing compliance, deduplicating contacts, and routing events both ways. See Twilio API Integration and Mailchimp API Integration for the underlying capabilities.
Get Twilio and Mailchimp Connected
If SMS and email run as separate channels in your business and you want them to act as one programme, we can build a custom Twilio to Mailchimp integration that handles compliance, routing, and triggers cleanly. We also connect Twilio to Klaviyo for behaviour-driven SMS alongside email, and WhatsApp to Mailchimp if WhatsApp is your primary messaging channel. The integrations overview covers the full range.
Written by
Alex
CEO
I’m a software developer and CEO of Digital Royalty, helping growing teams scale their SaaS platforms without losing quality, visibility, or control. I focus on building structured, maintainable systems with clear processes, reporting, and accountability. With over a decade of experience across agency and in-house roles, I specialise in delivering long-term, scalable solutions that support complex, evolving products.
