Email marketing still delivers the highest ROI of any digital channel—around $36 for every $1 spent. But the landscape has shifted dramatically with AI. Here’s our hands-on assessment of what actually works in 2026.
What We Tested
We ran real campaigns through 12 platforms over 90 days, measuring:
- Deliverability rates to Gmail, Outlook, and Yahoo
- AI-generated subject line performance (open rates)
- Personalization quality and relevance
- Time saved on campaign creation
- Actual conversion lift vs. manual campaigns
The Top Picks
1. Klaviyo — Best for E-commerce
Why it wins: Klaviyo’s predictive analytics are genuinely useful. The “expected date of next order” feature lets you time campaigns precisely, and their AI segments actually learn from your catalog.
Strengths:
- Deep Shopify/WooCommerce integration
- AI product recommendations that improve over time
- Predictive churn scoring that’s surprisingly accurate
Weaknesses:
- Pricing jumps significantly at 10K+ contacts
- Learning curve for the flow builder
Pricing: Free up to 250 contacts. Plans start at $20/month for 500 contacts.
2. Mailchimp with Intuit Assist — Best for Small Business
Why it wins: The integration of Intuit Assist has transformed Mailchimp. It now writes genuinely decent first drafts and the send-time optimization actually works.
Strengths:
- AI content generation that understands your brand voice
- Excellent deliverability (97%+ in our tests)
- Generous free tier
Weaknesses:
- Advanced automation requires higher-tier plans
- Template customization can be limiting
Pricing: Free up to 500 contacts. Essentials starts at $13/month.
3. ActiveCampaign — Best for Complex Automation
Why it wins: If you need sophisticated automation with AI-powered branching, ActiveCampaign delivers. Their predictive sending and content scoring save real time.
Strengths:
- Most powerful automation builder we tested
- AI predicts which contacts will engage
- CRM included at all tiers
Weaknesses:
- Interface can feel overwhelming
- Email designer is functional but not beautiful
Pricing: Starts at $29/month for 1,000 contacts.
4. Beehiiv — Best for Newsletters
Why it wins: Purpose-built for newsletter creators. AI writing assistance is baked in, monetization options are strong, and it just feels fast.
Strengths:
- Native sponsorship marketplace
- AI helps with headlines and summaries
- Built-in referral program
Weaknesses:
- Not designed for transactional emails
- Limited e-commerce integrations
Pricing: Free up to 2,500 subscribers. Scale at $39/month.
What About Pure AI Email Writers?
Tools like Lavender and Rasa.io focus specifically on AI-generated content:
Lavender excels at B2B sales emails—it scores your drafts and suggests improvements. We saw 23% higher reply rates using their recommendations.
Rasa.io curates personalized newsletters automatically. Great if you want to send valuable content without writing it yourself.
Our Testing Methodology
We didn’t just look at feature lists. For each platform:
- Deliverability test: Sent 5,000 emails to a panel of test addresses across major providers
- AI content test: Generated 50 subject lines and compared open rates to human-written alternatives
- Time study: Tracked hours spent creating equivalent campaigns
- Conversion tracking: Measured actual sales from campaigns (using e-commerce test accounts)
The Bottom Line
For most businesses, Klaviyo (e-commerce) or Mailchimp (everyone else) will be the right choice. The AI features in both have matured past gimmick status into genuinely useful tools.
If you’re sending to 100K+ contacts or need enterprise features, look at Customer.io or Braze—but expect to pay enterprise prices.
The biggest win from AI email tools isn’t the writing—it’s the optimization. Send time, subject lines, and segmentation improvements add up to real revenue.
Last updated: January 2026. We re-test quarterly.