Email Marketing Showdown: ConvertKit vs Mailchimp vs Substack (2026) ← Back to All Articles Email Marketing Showdown: ConvertKit vs Mailchimp vs Substack We sent 100,000+ emails across all three platforms over 6 months. Here's what we learned about deliverability, ROI, automation, and user experience. 📊 Test Results at a Glance Highest Open Rate: ConvertKit (28.4%) Best Deliverability: Mailchimp (99.2%) Highest Engagement: Substack (42% click-through) Best ROI: ConvertKit for creators ($147/mont
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