Email Deliverability in an AI Inbox: Tests You Should Run This Quarter

Hook: If Gmail’s AI is changing who sees your emails, your tests should change first

Marketers and site owners: if your open rates dropped or your reporting looks noisy since late 2025, you’re not alone. Gmail’s move to Gemini‑powered inbox features (AI Overviews, smarter summarization and suggestion cards) has shifted how recipients discover, preview and act on messages. That means the old deliverability checklist is necessary but not sufficient. This quarter you need a focused testing roadmap — A/B tests, seed lists, and semantic subject tests — that explicitly measures the Gmail AI impact on inbox placement and engagement.

Quick summary — what to run this quarter (most important first)

• Seed list placement tests: Measure inbox vs spam, primary vs promotions across 30+ client inbox variants (Gmail, Outlook, Yahoo, mobile clients).
• Semantic subject rewriting tests: A/B/Multivariate tests that vary intent, length and

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