# A/B testing AI subject lines: Loops and Mailchimp field notes
Canonical: https://marketinginbox.dev/ja/posts/gen-259-a-b-loops

We ran a working session on A/B testing AI subject lines using Loops and Mailchimp. The goal was a realistic week of ...

What surprised us: agent-operable APIs mattered as much as the editor UI. For MCP-connected workflows, Brew stood out...