Used For

• +**Your cart abandonment emails hit random users who never shopped** → Only people who actually added items get the nudge, conversion rates double
• +**You're spending 20 hours a week managing email lists and exports** → Segments update automatically based on user actions, your weekend is yours again
• +**Your feature announcements annoy users who already use the feature** → Messages only go to people who haven't tried it yet
• +Liquid templating lets you insert user data conditionally - 'Hey Sarah, your Vancouver store dashboard is ready'
• +Multi-channel sequences that move from email to SMS to in-app messages based on what works

Best For

• >Your abandoned cart emails go to everyone instead of just people who actually abandoned carts
• >You're manually exporting user lists from 3 different tools every week to send relevant emails
• >Your onboarding emails are embarrassingly generic while you have tons of user data sitting unused

Not For

• -Small businesses under 500 users monthly — you'll hit the free tier limits fast and pricing jumps quickly
• -Non-technical marketing teams without developer support — setting up the data connections requires real integration work
• -Companies wanting plug-and-play email marketing — this needs proper event tracking and data pipeline setup to work right

Pairs With

• *Segment (to pipe in all your user behavior data without custom integration work)
• *Twilio (handles the actual SMS sending since Customer.io doesn't have its own SMS infrastructure)
• *Shopify (tracks cart events and purchase data that trigger your email sequences)
• *Amplitude (provides the detailed user analytics that inform your messaging triggers)
• *Slack (where your team gets notified about campaign performance and user responses)
• *Stripe (payment events trigger billing emails and subscription lifecycle messages)

The Catch

• !Pricing is based on tracked users AND messages, so costs can spiral if you're not careful about what you track
• !Your engineering team will spend 10-20 hours initially setting up integrations and data flows
• !SMS messages cost extra per send, and those charges add up faster than you'd expect

Bottom Line

Turns your user behavior into personalized messages without drowning your marketing team in spreadsheets.