Knak / 2024-2026
AI Subject Line & Preview Assistant
Subject Line and Preview Text AI Assistant powered by Google Gemini. Achieved 50% increase in MAU/WAU.
Design Highlights
Overview
I designed Knak's first AI-powered feature: an in-editor assistant that generates tailored subject lines and preview text. Built on Google Gemini, it analyzes email content, applies Brand Voice rules, and incorporates the user's prompt to create relevant suggestions. The interaction model became the foundation for Knak's later AI features.
Challenge
Email marketers spend significant time crafting compelling subject lines and preview text that drive open rates. Writing effective subject lines requires balancing creativity with brand consistency, audience relevance, and campaign goals. As Knak's first AI feature, the challenge extended beyond the product itself—there was real hesitation about whether users would trust AI-generated content in their email workflows.
Approach
I placed the assistant directly inside the Knak Email Editor and designed it to offer guidance without boxing users in. It generates five immediate suggestions, then lets users keep chatting to refine tone, length, and direction. I also added account-level controls so customers could disable the feature while trust was still developing.
Solution
Built an AI assistant embedded in the email editor that generates five subject line and preview text suggestions using the context of the email body content, configured Brand Voice attributes and rules, and any additional prompt instructions from the user. The conversational interface allows users to iterate beyond the initial suggestions—refining tone, adjusting length, or exploring different creative directions. The assistant pulls brand context automatically so suggestions are on-brand without requiring users to specify guidelines each time.
Impact
Achieved 50% increase in MAU/WAU and 60% monthly active account usage, proving strong adoption for Knak's first AI feature. Most customers who initially hesitated began to trust the AI and turned the feature on, with many stating they use it for all emails or to A/B test different subject line options. The feature paved the way for every subsequent AI feature at Knak—each has built on the foundation established here, and all features now work together in powerful ways. AI Email Generation automatically generates subject lines and preview text, and Brand Voice rules are included as context across all AI content generation.
Key Learnings
Building Knak's first AI feature was a learning experience in designing for trust. Adding the ability to disable the feature gave customers control, but most chose to keep it on once they experienced the value. The biggest barrier to adoption wasn't AI trust—it was that many customers still rely on external copy creation due to legal approvals and internal policies. Starting with a focused, high-value use case (subject lines) was the right entry point for AI at Knak, establishing patterns and building confidence that enabled more ambitious AI features.