Best Email Marketing Software 2026: Deliverability Tested
Inbox placement rates tested across Gmail, Outlook, and Apple Mail for 8 platforms.
Why Deliverability Is the Only Metric That Matters
An email marketing platform with a 95% inbox placement rate will outperform a platform with a 75% inbox rate regardless of any other feature. Yet most comparisons focus on automation builders, template libraries, and pricing -- not the one metric that determines whether your emails actually reach subscribers.
We used Emailtooltester's methodology to test inbox placement across Gmail, Outlook, Yahoo, and Apple Mail for 8 platforms, sending 1,000 test emails per provider over 30 days.
Deliverability Test Results
| Platform | Gmail | Outlook | Yahoo | Apple Mail | Overall |
|---|---|---|---|---|---|
| Kit (ConvertKit) | 98.2% | 96.4% | 97.1% | 99.1% | 97.7% |
| ActiveCampaign | 97.8% | 95.9% | 96.8% | 98.7% | 97.3% |
| Klaviyo | 97.2% | 95.1% | 96.2% | 98.1% | 96.7% |
| Mailchimp | 96.1% | 94.2% | 95.4% | 97.3% | 95.8% |
| AWeber | 95.6% | 93.4% | 94.8% | 96.2% | 95.0% |
| GetResponse | 94.8% | 92.3% | 93.7% | 95.9% | 94.2% |
| Constant Contact | 94.2% | 92.7% | 93.1% | 95.4% | 93.9% |
| Brevo (Sendinblue) | 93.4% | 91.8% | 92.6% | 94.7% | 93.1% |
The Winner: Kit (ConvertKit)
Kit leads on deliverability across every inbox provider. Their dedicated IP infrastructure, strict list hygiene enforcement, and creator-focused sending patterns result in the highest inbox placement rates in the industry. For newsletter businesses where deliverability is existential, Kit is the clear choice.
Best for E-commerce: Klaviyo
Klaviyo's Shopify and WooCommerce integrations are unmatched. Real-time behavioural triggers, predictive analytics, and revenue attribution make it the dominant choice for e-commerce email marketing.
Data sources: Emailtooltester Email Deliverability Study 2025; Litmus State of Email 2024; independent testing April 2026.
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