10 Email Marketing Software That Integrate with Customer.io
By Tazmeen
Email marketing remains one of the most powerful marketing channels in 2026, with global email users expected to grow significantly in the coming years. According to the latest email marketing statistics, almost three-quarters of marketers say email is their go-to channel for ROI, with many reporting up to a 2× improvement year over year. Customer.io is amazing at what it does. That is, it is amazing at doing behavioral email automations powered by product data. But here is what teams find when they go all in on such Software: Customer.io is great for sending emails triggered by a user action, but it is not a solution to every email marketing need.
Understanding Customer.io's Email Strengths (And Gaps)
Where Customer.io Excels
Behavioral Triggering: Send emails based on any user action or event
Data Integration: Connect product usage data seamlessly
Visual Workflow Builder: Create sophisticated customer journeys
Multi-Channel Coordination: Email + SMS + Push + In-App messaging
Segmentation: Build complex audience segments with ease
Developer-Friendly: Robust API and webhook architecture
Common Customer.io Email Challenges
Deliverability Concerns: While functional, Customer.io isn't a dedicated email delivery service. Teams sending high volumes or critical transactional emails often need specialized infrastructure.
Template Design Limitations: The email builder works fine, but design-focused teams sometimes want more advanced template systems or brand management Software.
Interactive Email Capabilities: Customer.io sends traditional HTML emails. If you want recipients to complete forms, book appointments, or shop directly in emails, you need AMP technology.
Warming Up New Domains: Customer.io doesn't provide dedicated IP warming services or deliverability consulting that specialized platforms offer.
How These Integrations Work
Integration 1: SMTP Relay Customer.io sends emails through your email platform’s SMTP instead of its own. Improves deliverability and reliability for transactional emails.
Integration 2: Data Pipeline Export Customer.io sends contacts and segments to your email tool via API/webhooks. Let's you run campaigns in the email platform using Customer.io data.
Integration 3: Reverse ETL via Data Warehouse Customer.io syncs data to a warehouse, and the email platform pulls from it. Best for advanced, unified campaigns using combined customer data.
The 10 Specialized Email Platforms for Customer.io
1. Mailmodo
Integration Type: Data export via webhooks, API, or data warehouse sync
Mailmodo is an AI email marketing software that helps you create, automate, and optimize campaigns effortlessly. From planning strategy to writing copy and building journeys, Mailmodo’s AI Agents handle it all, with no technical expertise needed. It’s the fastest way to send smart, interactive, and high-performing emails.
Key Features
AI Email Assistant: Plan strategy, write copy, and build entire campaigns with AI guidance
AI Email Assistant: Auto-generate campaigns, subject lines, and copy variations
No-Code Template Builder: 500+ conversion-tested templates
Customer.io Webhook Integration: Trigger Mailmodo campaigns from Customer.io events
Smart Automation: AI-driven journeys with behavioral adaptation
Form Response Sync: Push responses back to Customer.io profiles
Managed Deliverability: Expert team monitors sender reputation
Real Impact
Razorpay: 257% more survey completions with in-email forms
Mudrex: 280% webinar registration increase
Preplaced: 5X email-to-sale conversion improvement
Pricing
Free: Forever-free Plan with limited features
Lite: $27/month - Designed for solo marketers and small teams, includes 500 contacts
Pro: $79/month - Pro plan comes with a 21-day free trial
Max: $99/month - Custom Pricing
Perfect For: Growth-focused businesses, SaaS companies, and marketers who want maximum conversions through AI-powered, interactive email experiences triggered by Intercom events.
Integration Setup: Export Customer.io segments via webhook to Mailmodo. Use Customer.io events to trigger Mailmodo campaigns. Sync form submissions back to Customer.io profiles for continued behavioral targeting. Setup takes 60-90 minutes.
2. Mailchimp
Integration Type: API integration, Zapier, or custom webhooks
Mailchimp has a very user-friendly interface with gorgeous templates, which makes it perfect for email marketing for startups. While Customer.io excels at behavioral automation, Mailchimp provides user-friendly campaign creation, extensive template libraries, and proven deliverability that businesses trust.
Key Features
Drag-and-Drop Builder: Intuitive email editor with 100+ templates
Marketing CRM: Built-in CRM for customer relationship management
Audience Segmentation: Advanced targeting with Customer.io data
AI Content Generation: Auto-create subject lines and email copy
Marketing Automation: Pre-built customer journey templates
Multi-Channel Marketing: Email, social ads, landing pages, postcards
Detailed Analytics: Comprehensive reporting and revenue tracking
Global Deliverability: 99%+ delivery rate with massive infrastructure
Real Impact
Trusted by 11+ million businesses worldwide
99% average delivery rate across billions of emails
Industry-standard platform with extensive third-party integrations
Pricing
Free: Up to 500 contacts, 1,000 monthly emails
Essentials: $13/month for 500 contacts
Standard: $20/month for 500 contacts (includes automation)
Premium: $350/month for 10,000 contacts (advanced features)
Perfect For: Teams wanting a recognizable, proven email marketing platform with superior ease-of-use alongside Customer.io's behavioral automation capabilities.
Integration Setup: Connect via Zapier or API to sync Customer.io segments to Mailchimp audiences. Export behavioral data to create targeted Mailchimp campaigns. Set up webhooks for engagement tracking. Setup takes 45-75 minutes.
3. Postmark
Integration Type: Custom SMTP server in Customer.io
The sole purpose of the Postmark platform is to send transactional emails at 99.99% uptime and sub-second speeds. While the Customer.io platform is sending behavioral Emails, the task of sending transactional Emails instantly is done by the Postmark platform.
Key Features
99.99% Uptime SLA: Guaranteed reliability for mission-critical emails
Sub-Second Delivery: Industry-leading send speeds
Transactional-Only Infrastructure: Dedicated servers that ISPs trust implicitly
45-Day Message History: Detailed logs for every email sent
Spam Score Testing: Preview how ISPs will treat your emails
Bounce Categorization: Understand exactly why emails fail
Sandbox Testing: Test integration without sending real emails
Real Impact
"Much better than SendGrid, which had endless deliverability problems. Postmark's deliverability is fantastic, and their UI is intuitive." – G2 Reviewer.
99.99% uptime guarantee with transparent status page
Sub-second delivery for time-sensitive notifications
Pricing
Free: 100 emails/month trial
Basic: $15/month for 10,000 emails
Growth: Scales based on volume
Enterprise: Custom pricing for high volumes
Perfect For: SaaS teams using Customer.io who need bulletproof delivery for critical transactional emails like password resets, receipts, and security alerts.
Integration Setup: In Customer.io, go to Settings > Workspace Settings > Email > Custom SMTP Settings. Add Postmark credentials, set up webhooks for tracking. Customer.io creates emails, Postmark delivers them. Setup takes 15-30 minutes.
4. SendGrid
Integration Type: Custom SMTP configuration + webhook sync
SendGrid provides enterprise-grade email infrastructure with deep analytics, robust APIs, and proven scalability. When the emailing capabilities of Customer.io are insufficient for high-volume sending or detailed delivery insights, that is when SendGrid's infrastructure steps in. The platform handles billions of emails monthly for companies like Uber, Airbnb, and Spotify.
Key Features
Scalable Infrastructure: Handles billions of emails monthly
Dedicated IP Management: Control sender reputation precisely
Advanced Analytics: Detailed metrics on deliverability, engagement, and geographic data
Subuser Management: Separate sending streams for different teams/purposes
Template Engine: Version control and dynamic content
Event Webhooks: Real-time delivery, bounce, and engagement tracking
Marketing Campaigns: Built-in marketing automation for non-behavioral campaigns
Real Impact
Powers email for Uber, Airbnb, Spotify, and thousands of enterprises
Handles billions of emails monthly with 99%+ deliverability
Enterprise-grade infrastructure trusted by Fortune 500 companies
Pricing
Free: 100 emails/day permanently
Essentials: $19.95/month for 50,000 emails
Pro: $89.95/month for 100,000 emails
Premier: Custom pricing for enterprise volumes
Perfect For: High-growth SaaS companies outgrowing Customer.io's sending infrastructure that need enterprise-level deliverability and detailed analytics.
Integration Setup: Configure SendGrid as a custom SMTP in Customer.io. Set up webhook endpoints for engagement tracking. Optional: Create a subuser specifically for Customer.io sends. Setup takes 45-90 minutes with subuser configuration.
5. HubSpot
Integration Type: Native two-way integration via HubSpot App Marketplace
HubSpot has the most advanced marketing platform that includes the functions of CRM, analytics, and many more that are combined into a system that is accessed via the web and cloud services. Though the specialty of Customer.io is behavioral automation emails, HubSpot offers a full-blown marketing platform.
Key Features
Complete Marketing Suite: Email, CRM, automation, landing pages, forms, ads, SEO
Two-Way Data Sync: Automatic contact and event synchronization with Customer.io
Visual Workflow Builder: Drag-and-drop automation for complex journeys
Smart Content: Personalization based on lifecycle stage and behavior
Attribution Reporting: Track revenue across all marketing channels
Sales Integration: Seamless handoff from marketing to the sales team
Content Management: Blog, website, and landing page. Software included
AI-Powered Features: Content generation, send time optimization, predictive scoring
Real Impact
194,000+ customers across 120+ countries globally
Unified platform eliminates the need for multiple marketing Software
Deep native integration provides seamless data flow
Pricing
Free: Basic CRM and email (2,000 sends/month)
Starter: $20/month for 1,000 contacts
Professional: $890/month for 2,000 contacts (full marketing suite)
Enterprise: $3,600/month (advanced features, dedicated support)
Perfect For: Companies wanting a complete marketing platform that integrates natively with Customer.io for unified customer data and comprehensive marketing capabilities.
Integration Setup: Install the HubSpot app from the Customer.io marketplace. Configure two-way sync for contacts and events. Map custom properties between platforms. Setup takes 1-2 hours with full bidirectional sync.
5. Mailgun
Integration Type: Custom SMTP + comprehensive webhooks
Mailgun offers a resilient email infrastructure with a developer-focused approach in mind: flexible APIs and a plethora of helpful documentation resources at their disposal to handle even the most complicated email-related tasks, unlike what Customer.io offers in terms of actionable and straightforward workflows designed specifically with marketers in mind.
Key Features
Powerful Email API: RESTful API for complete programmatic control
Inbound Email Parsing: Route and parse incoming emails
Email Validation API: Verify addresses before sending
Detailed Logs: 30-day searchable email history
Tag-Based Tracking: Organize and analyze emails by custom tags
Scheduled Sending: Queue emails for future delivery
Template Variables: Dynamic content with simple syntax
Suppression Management: Automatic bounce and complaint handling
Real Impact
Clean API with excellent documentation, loved by developers
Flexible webhook system for real-time event tracking
Powerful inbound email parsing for reply handling
Pricing
Trial: 5,000 emails/month free for 3 months
Foundation: $35/month for 50,000 emails
Growth: $80/month for 100,000 emails
Scale: Custom pricing for enterprise volumes
Perfect For: Technical teams needing programmatic email control, inbound parsing, and API-first workflows alongside Customer.io's behavioral automation.
Integration Setup: Add Mailgun SMTP credentials to Customer.io custom SMTP. Configure webhooks for event tracking. Optional: Set up inbound routing for reply handling. Technical setup takes 1-2 hours.
6. Campaign Monitor
Integration Type: API export or Zapier integration
Campaign Monitor excels at one thing: creating gorgeous, on-brand emails with minimal effort. While Customer.io handles behavioral triggering, Campaign Monitor provides superior template systems, brand management, and design Software that make it easy for non-designers to create professional emails that match your brand perfectly.
Key Features
Drag-and-Drop Builder: Intuitive visual email editor
Brand Templates: Save and reuse branded designs across the team
Client Management: Perfect for agencies managing multiple brands
Personalization Tags: Dynamic content with simple syntax
Journey Designer: Visual automation builder for campaigns
Timezone Sending: Deliver emails at optimal local times
Link Tracking: Detailed click analytics with link performance
Spam Testing: Preview deliverability before sending
Real Impact
100+ professionally designed templates with easy customization
Above-average email engagement rates reported by users
Design-focused interface loved by marketing teams
Pricing
Basic: $12/month for 2,500 contacts
Unlimited: $29/month for 2,500 contacts (unlimited sends)
Premier: $149/month (advanced features, priority support)
Scales based on contact count
Perfect For: Design-conscious teams and agencies who use Customer.io for triggering but want superior template management and brand control.
Integration Setup: Use Zapier to sync Customer.io segments to Campaign Monitor lists. Trigger Campaign Monitor campaigns based on Customer.io events. Setup takes 30-60 minutes with pre-built Zaps.
7. Sender
Integration Type: API integration or Zapier
Sender provides professional-level email marketing services at highly economical prices with a truly useful free plan that comes with 15,000 emails per month. Though available plans from Customer.io begin at a surprisingly low rate of $100 for 5,000 profiles a month, Sender costs a fraction for its unlimited contacts/sending allowance.
Key Features
Unlimited Contacts: Pay based on sends, not list size
Drag-and-Drop Builder: Easy email creation for non-designers
SMS Marketing: Add text messaging to email campaigns
Automation Workflows: Welcome series, cart abandonment, etc.
Landing Pages: Built-in page builder for lead capture
Pop-ups: Website forms for subscriber growth
Detailed Analytics: Track opens, clicks, revenue
Integrations: Connect with 1,500+ apps via native integrations
Real Impact
Free tier includes 15,000 emails/month with no time limit
Unlimited contacts on all plans (no per-profile charges)
80-90% cost savings vs. Customer.io for similar volumes
Pricing
Free: 15,000 emails/month forever, unlimited contacts
Standard: $15/month for 60,000 emails
Professional: $29/month for 120,000 emails
Enterprise: Custom pricing for high volumes
Perfect For: Startups and small businesses using Customer.io who need affordable email marketing for newsletters and promotions without paying per contact.
Integration Setup: Connect via API or Zapier. Sync Customer.io segments to Sender lists. Trigger campaigns based on behavior. Setup takes 20-40 minutes.
8. EmailOctopus
Integration Type: Import contacts via CSV or API
EmailOctopus offers simplicity together with the infrastructure of Amazon SES to provide an enterprise-class sending solution at very affordable prices. While Customer.io excels at the complex behavior workflows, EmailOctopus shines at simply sending newsletters, announcements, and campaigns where complex triggering isn't required.
Key Features
Built on Amazon SES: Enterprise infrastructure at startup prices
Drag-and-Drop Builder: Clean, simple email editor
Landing Pages: Customizable subscription forms
Automation Workflows: Basic triggered sequences
Segmentation: Tag-based audience targeting
GDPR Compliant: Built with EU privacy standards
Zapier Integration: Connect to 5,000+ apps
Embedded Forms: Add signup forms to your website
Real Impact
Amazon SES infrastructure means wholesale pricing
Excellent deliverability with minimal setup complexity
60-80% cost savings vs. traditional email platforms
Pricing
Free: 2,500 subscribers, 10,000 emails/month
Pro: $8/month for 5,000 subscribers
Scaling: $20/month for 10,000 subscribers
Continues scaling affordably with list size
Perfect For: Teams using Customer.io for behavioral emails who need simple, affordable newsletter and broadcast capabilities.
Integration Setup: Export segments from Customer.io, import to EmailOctopus via CSV or API. Schedule regular syncs via Zapier. Simpler workflows mean faster setup—15-30 minutes.
9. ActiveCampaign
Integration Type: API integration, Zapier, or custom webhooks
ActiveCampaign is an all-in-one platform that comprises email marketing, marketing automation, sales CRM, and messaging, which offers 900+ pre-built automation recipes. As Customer.io is capable of handling event-driven triggering, ActiveCampaign is better at performing complicated nurture campaigns, scoring leads, and sales pipelining that is beyond email automation.
Key Features
900+ Automation Recipes: Pre-built workflows for every business scenario
Predictive Sending: AI determines optimal send times per recipient
Lead Scoring: Automatic qualification based on behavior and engagement
Sales CRM Integration: Connect marketing automation to the sales pipeline
Site Tracking: Monitor website activity for behavioral triggering
Dynamic Content: Personalize emails based on 1,000+ data points
Split Testing: A/B test entire automation workflows, not just emails
Conversation Automation: SMS, chat, and social messaging included
Real Impact
185,000+ businesses in 170+ countries use ActiveCampaign
Average 99% email delivery rate with a dedicated deliverability team
Named #1 email marketing software by G2 for 8 consecutive years
Pricing
Starter: $15/month for 1,000 contacts (email marketing only)
Plus: $49/month for 1,000 contacts (CRM + automation)
Professional: $79/month for 1,000 contacts (advanced features)
Enterprise: $145/month for 2,500 contacts (custom everything)
Perfect For: Growth-focused B2B businesses needing sophisticated marketing automation and sales CRM alongside Customer.io's behavioral email triggering capabilities.
Integration Setup: Connect via API or Zapier to sync Customer.io behavioral data to ActiveCampaign. Create automation workflows triggered by Customer.io events. Set up lead scoring based on combined data. Setup takes 60-90 minutes.
Integration Strategies for Maximum Impact
Strategy 1: Deliverability Enhancement Set up: Use Customer.io for triggers and route emails through SMTP providers like SES or SendGrid. Benefits: Better inbox placement, stronger sender reputation, and reliable delivery.
Strategy 2: Conversion Optimization Set up: Customer.io sends triggered segments to an email platform for campaigns. Benefits: Higher conversions, reduced friction, and better user actions from emails.
Strategy 3: Cost Optimization Set up: Use Customer.io for automation and low-cost Software for bulk emails. Benefits: Significant cost savings while maintaining campaign performance.
Strategy 4: Design System Management Set up: Use Customer.io for logic and a design-focused tool for templates. Benefits: Consistent branding and easier email creation for teams.
Final Thoughts
Customer.io is very powerful at behaviorally driven, product-related email automation and excels when you have mail that has to be triggered by actual activity. It provides functionality regarding segmentation, journeys, and event-related communication that many traditional mail services do not provide.
At the same time, it is not meant to be a solution for all the needs of email marketing, such as design systems, bulk campaigns, deliverability management, or cost-effective delivery. This is why many people end up using Customer.io in combination with another email provider to form a more comprehensive system for their email marketing.