HTML Email Debugger

Validate HTML email markup against real-world email client rendering constraints and generate deterministic, client-aware failure reports.

This Actor analyzes raw HTML email source code and applies a fixed rule set to identify structural, CSS, media, and compatibility issues that cause emails to break across clients such as Outlook, Gmail, Apple Mail, and Yahoo.

It is designed for precision, not design guidance.

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What This Actor Does

• Validates HTML email structure using deterministic rules
• Detects client-specific rendering failures
• Identifies exact failing elements with inspectable locations
• Produces a binary verdict (PASS / FAIL)
• Outputs structured, machine-readable diagnostics

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Supported Email Clients

• Outlook (Windows / Word rendering engine)
• Gmail (Web and Mobile)
• Apple Mail
• Yahoo Mail

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Built-In Test Presets

To support regression testing and deterministic validation, the Actor includes built-in presets:

• broken-email-v0.1 — Deliberately broken email (expected FAIL)
• clean-email-v0.1 — Minimal compliant email (expected PASS)

Presets can be selected directly in the Input UI.

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Input Parameters

Preset (Optional)

• preset
  • none (default)
  • broken-email-v0.1
  • clean-email-v0.1

When a preset is selected, custom HTML input is ignored.

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Custom HTML Validation

• emailHtml (string)
  Raw HTML email source to validate. Required when preset is none.

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Validation Options

• intendedClients
  Target email clients to validate against
  (default: outlook, gmail)

• strictMode
  Fail if any critical violations are detected
  (default: true)

• maxViolations
  Maximum number of violations to record
  (default: 100)

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Output

Each run produces a single dataset item with:

• verdict — PASS or FAIL
• failureCount — Total violations detected
• violations — Detailed rule-based failures
• element locations — Tag, selector, snippet, byte offset
• metadata — Rule version, preset used, hash, timestamp

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Rule Set

• 15 deterministic rules (v0.1)
• Covers structure, CSS, media, links, and compatibility
• No heuristics, scoring, or LLM-based analysis
• Same input always produces the same output

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What This Actor Does Not Do

• No visual previews
• No template generation
• No accessibility scoring
• No autofix or code rewriting
• No LLM interpretation

This is a debugger, not a designer.

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Legal and Compliance

• Processes only provided HTML input
• No scraping or external requests
• No personal data stored
• GDPR-friendly by design

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Performance

• Typical runtime: under 1 minute
• Memory usage: under 4 GB
• Deterministic and repeatable outputs
• Suitable for CI and automated pipelines

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Versioning

• v0.1 — Initial deterministic rule set
• Future versions will expand rules only with explicit versioning

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Final Note

HTML email rendering failures are silent and costly.

This Actor exists to surface those failures deterministically, explain exactly why they occur, and make results trustworthy without interpretation.