Email design prompts. For Klaviyo + Claude.
Build a section-by-section email brief: subject, preheader, hero, CTA, dark-mode notes, alt text, spam-trigger guard. Browser-only.
Type, vertical, sections, subject.
Paste into Claude or Klaviyo AI.
Three reference briefs.
Type: welcome series, day 1. Vertical: DTC beauty. Tone: warm-personal. Hero: full-width product photo. Subject (5 variants, curiosity): "The calm starts here", "Welcome to the linen-soft kind", etc. Preheader: "Welcome to the calm." Sections: hero, founder note, ingredient transparency, social proof, single CTA "Shop the tonic", footer with unsubscribe. Standard length, mobile-first.
Type: abandoned cart. Vertical: DTC fashion. Tone: direct. Hero: lifestyle scene. Subject (5 variants, urgency): "Linen sells out by Sunday", "Your cart is waiting", etc. Preheader: "Cart saves for 7 days." Sections: hero, product-grid (the cart items), single CTA "Complete checkout", footer. Brief length. Show specific cart items with image, name, price.
Type: launch announcement. Vertical: B2B SaaS. Tone: direct-utilitarian. Hero: minimal logo + headline. Subject (5 variants, benefit): "Close books 4 days faster", "New in Tallyloop: Stripe sync", etc. Preheader: "Now in beta." Sections: hero, value-prop, single CTA "Join the beta", footer. Standard length. Single screenshot of the new feature.
Email is a format, not a layout.
An email-design prompt that produces deliverable HTML on the first pass treats email as a constrained-medium problem, not a web-design problem. Mobile-first 320-pixel viewport, single column, table-based fallback for Outlook, dark-mode meta tags, alt text on every image, plain-text version alongside HTML, single primary CTA, sub-50-character subject line, sub-90-character preheader, physical mailing address in the footer for CAN-SPAM compliance, unsubscribe link in plain readable color. The prompt should encode all of these as defaults so the generated email passes a Litmus or Email on Acid render check on the first try.
Subject does not equal preheader does not equal first line
Three separate copy decisions, each with its own job. Subject decides the open. Preheader supports the subject with the second hook. The first line of the email body confirms the reader made the right choice and previews the value. A prompt that treats these as one decision produces emails where the subject and preheader repeat, then the first body line restates the subject again. Specify each independently. Tools like Klaviyo and Postscript let you A/B test subject + preheader as a pair; treat them as a unit when testing, three units when writing.
Mobile-first 320 pixels
About 60-70 percent of email opens happen on mobile, with iPhone alone accounting for 40-50 percent. The design floor is the iPhone SE 320-pixel viewport. Single column, 16-pixel body type minimum, 44×44-pixel tap targets, no tables nested more than two deep, no hover-only states. The prompt should specify mobile-first explicitly; without that, the LLM defaults to desktop-width tables that break at 320 pixels.
Image-blocked fallbacks
About 25 percent of email clients block images by default, and Apple Mail Privacy Protection masks open tracking. Every email must read with images blocked. Functional alt text on every image (alt="dropdown chamomile sleep tonic in a frosted bottle" beats alt="product"). Headlines and CTA copy live as live HTML text, not as images. Background colors fall back to a solid color when the background image fails to load. Without these, image-blocked recipients see broken-image placeholders and unsubscribe.
Single primary CTA
One email, one decision. Multiple CTAs split attention and reduce overall click-through rate. Litmus's 2024 study found single-CTA emails outperformed multi-CTA emails by 12-30 percent on click-through rate across DTC, SaaS, and education verticals. The exception is a curated digest where each section has its own CTA; in that case the digest itself is the format and the multi-CTA pattern is expected. The prompt should specify one primary CTA unless the email type is a digest.
Plain-text version
Spam filters score multipart emails (HTML + plain text) higher than HTML-only emails. The plain-text version is not the HTML stripped of tags; it is the email rewritten for plain display - line breaks, simple paragraph structure, plain URLs. Klaviyo and Anthropic's Claude both generate plain-text versions when the prompt asks for them. Without the request, you get HTML-only output that hits spam folders more often.
Test before send
Render the email in Litmus or Email on Acid across 30+ client+OS combinations. Apple Mail dark mode is the most common breakage; Outlook 2019 desktop is the second. Klaviyo's built-in preview catches the high-volume clients. Without the render check, you ship and discover the dark-mode logo invert in production. The prompt should request a Litmus or Email on Acid render gate as part of the workflow.
Related tools: Landing page prompt generator for the post-click destination. Headline analyzer for the subject lines. UTM builder for the email tracking. Brand voice prompt generator for the tone. Email marketing service for the run-it-for-me version.
Five answers.
What is an email design prompt generator?
A tool that assembles a structured spec describing an email so that an LLM-driven builder like Claude, v0.dev, or an in-platform Klaviyo AI assistant can generate the email HTML or design layout. The prompt covers email type, brand vertical, tone, hero block style, sections, subject line, preheader, length, and accessibility notes.
Why are subject and preheader specified separately?
Subject and preheader play different roles. The subject is the open-decision; the preheader is the supporting context shown next to or below the subject in most inboxes. They should reinforce each other, not repeat each other. A subject of "Your sleep is on us tonight" paired with a preheader of "Your sleep is on us tonight" wastes the second line; pair it with "Free 28-night sample, ships tomorrow" to reinforce the offer.
What email types does the prompt handle?
Welcome series, abandoned cart, post-purchase, winback, launch announcement, weekly digest, and transactional confirmation. Each type has a different structural pattern: welcome series leads with brand story, abandoned cart leads with the specific cart items, transactional leads with the action confirmation. The prompt encodes the right structure for each type.
Why does the prompt include dark-mode notes?
Apple Mail and Gmail's iOS app both auto-invert colors in dark mode unless the email opts out. Logos with transparent backgrounds get inverted into hard-to-read shapes; dark text on light backgrounds becomes light text on dark backgrounds. The prompt includes meta tags for color-scheme and supported-color-schemes so the email renders predictably in both modes.
Does this tool save my prompts?
No. Every value you enter and every prompt assembled lives in memory for this browser tab only. Nothing is transmitted to a server, stored in a database, or synced across devices. Close the tab and the data is gone.
One email is a unit; lifecycle is the system.
Our email-marketing engagements build the full Klaviyo or Postscript flow library: welcome 5-part, abandoned cart 3-step, post-purchase 4-part, winback 2-step. Pre-built segments, A/B testing schedule, render-tested templates.