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Highlights

• Added Major validation engine refresh across HTML, CSS-related checks, fonts, accessibility, mobile, links, analytics, images, viewport audit, and the pre-send checklist.
• Added Stronger safeguards for request handling, CSRF validation, DNS-only deliverability requests, viewport auditing, and external asset probing.
• Improved Result quality, line-number accuracy, false-positive handling, security hardening, and performance across large or complex HTML email templates.

Core Platform & Security

• Updated Main validation request handling in check.php.
• Separated DNS-only deliverability validation from normal HTML validation.
• Improved CSRF handling for both regular checks and DNS-only requests.
• Added safer request normalization for raw HTML, escaped HTML, and base64-like submissions.
• Improved server-side sanitization before DOM parsing and preview rendering.
• Improved Security protections for submitted HTML.
• Neutralizes active tags such as script, iframe, object, embed, form, base, and applet before normalized parsing.
• Removes inline event handlers during safe preview/validation processing.
• Blocks scriptable URL schemes such as javascript: and vbscript:.
• Blocks unsafe data: navigation links while keeping image data URI detection available to validators.

HTML Validation

• Updated HTML validation with a more robust structural scanning algorithm.
• Improved handling of Outlook/MSO conditional comments.
• Prevents Outlook conditional comments from being counted as normal HTML comments.
• Improved detection of unclosed, mismatched, and unterminated HTML tags.
• Improved table-context validation for <table>, <tr>, <td>, and <th>.
• Reduced false positives for valid email-client-specific markup.
• Improved masking of comments, style blocks, script blocks, CDATA, and conditional comments while preserving line numbers.
• Updated HTML result severity handling.
• Legacy tags such as <font> and <center> are now treated as compatibility guidance instead of hard failures.
• <div> usage is now reported as email-layout guidance instead of a hard compatibility warning.
• Table role recommendations are kept as neutral guidance for layout-table accessibility.
• Improved HTML result ordering, grouping, and line-jump consistency.

Viewport Audit

• Updated Viewport audit for desktop, tablet, and mobile rendering checks.
• Improved sandboxed iframe rendering for multiple viewport widths.
• Improved image sharpness checks using effective pixels per displayed pixel.
• Improved text legibility checks with viewport-specific minimum font-size thresholds.
• Improved tap-target checks for tablet and mobile.
• Added server-side summary and fix-message endpoints for more consistent recommendations.
• Improved source line annotation for images, text elements, and links.
• Added client-side fallback line mapping when server-side annotations are unavailable.
• Fixed Security-check failures caused by DNS-only form state leaking into the main validation flow.

Font Validation

• Updated Font validation with a production-ready 2025 rule set.
• Detects web font references, external font stylesheet links, @import, and @font-face usage.
• Detects missing font-display in @font-face blocks.
• Detects duplicate @font-face declarations by family, weight, and style.
• Flags insecure HTTP font URLs and embedded data-URI fonts.
• Flags legacy TTF/OTF font sources and recommends WOFF2/WOFF where web fonts are used.
• Detects heavy Google Fonts requests and excessive family variants.
• Detects font-family declarations without generic fallbacks.
• Detects unquoted multi-word font family names.
• Detects excessive primary font families, advanced typography properties, variable font settings, shorthand font declarations, zero font size, and disabled text-size adjustment.
• Detects image alt-text styling assumptions that may not work reliably in email clients.

Accessibility Validation

• Updated Accessibility validation with deeper email-specific accessibility checks.
• Improved DOM-to-source line mapping for more accurate result locations.
• Improved readability snapshot with Flesch-Kincaid Reading Ease, Flesch-Kincaid Grade Level, Gunning Fog Index, SMOG Index, and Automated Readability Index.
• Improved language detection and <html lang> validation.
• Checks for missing <title> and missing UTF-8 charset declarations.
• Checks heading hierarchy, multiple H1 usage, and heading level jumps.
• Checks Outlook-safe heading and paragraph spacing resets.
• Checks layout tables for missing role="presentation" or role="none".
• Checks empty links, vague link text, linked image alt text, and link title usage.
• Checks missing image alt text while respecting explicitly decorative images.
• Checks low text contrast where inline foreground and background colors can be evaluated.
• Detects removed focus outlines.
• Detects right-to-left content without matching dir="rtl".
• Improves dark-mode guidance for color-scheme declarations and dark-mode CSS.

Mobile Validation

• Updated Mobile validation with modern responsive-email checks.
• Validates viewport meta presence and checks for width=device-width.
• Flags missing initial-scale, disabled zoom, fixed viewport widths, and deprecated viewport properties.
• Detects media queries and risky device-width breakpoints.
• Detects disabled text-size adjustment.
• Flags small font-size declarations and low line-height values.
• Checks CTA-style links for small tap-target risk.
• Flags hover-only interactions that may fail on touch devices.
• Detects fixed-width tables, large min-width values, non-fluid large images, and long unbroken text segments.
• Flags iOS telephone auto-link suppression when it may reduce mobile usability.

Link Validation

• Updated Link validation with a safer, faster, time-budgeted reachability engine.
• Uses bounded parallel HTTP/HTTPS checks with a hard wall-clock budget.
• De-duplicates URLs before network checks.
• Caps the number of external network checks to keep scans responsive.
• Classifies timeouts, DNS failures, and connection failures as “Not checked” instead of false “Unreachable” failures where appropriate.
• Improves handling of HTTP HEAD limitations using a controlled fallback strategy.
• Updated Per-link validation rules.
• Checks missing and empty href attributes.
• Checks invalid or unsupported protocols.
• Checks insecure http:// links.
• Checks malformed mailto:, telephone, SMS, and related link formats.
• Checks missing and empty targets where applicable.
• Preserves detailed per-link reporting with line numbers, status, HTTP result, and remediation notes.

Analytics & Tracking Validation

• Updated Analytics validation and platform detection.
• Improved tracking pixel detection.
• Improved link-level platform detection by host and query parameters.
• Improved validation of required tracking parameters.
• Improved handling of empty, fragment-only, malformed, non-HTTP, and whitespace-corrupted tracking URLs.
• Improved summary counters for tracked links, untracked links, invalid tracking parameters, and missing required parameters.
• Improved machine-readable export data for API usage.
• Added Expanded analytics platform definitions.
• Updated tracking pixel patterns.
• Updated host detection patterns.
• Updated required-parameter definitions for supported analytics and email platforms.

Image Validation

• Updated Image validation with a faster and safer validation engine.
• Uses strict execution time budgeting to keep large scans responsive.
• Uses sampled, parallel image reachability checks when network validation is enabled.
• Limits external checks by image count, host count, concurrency, and request timeout.
• Improves handling of unreachable images, skipped checks, and network-limited scans.
• Improves image source validation for missing, empty, insecure, relative, protocol-relative, CID, and data-URI sources.
• Checks missing, empty, overly long, and linked-image alt text.
• Checks width and height attributes, empty dimensions, and non-numeric dimensions.
• Flags risky image styling such as padding, margins, and unsupported alt-text styling.
• Detects possible tracking pixels.
• Flags image formats with poor or mixed email-client support.
• Flags base64 images, CID images, animated GIF caveats, and responsive image features with partial support.
• Updated Image-Meta updated for safer metadata probing.
• Restricts probes to HTTP/HTTPS URLs.
• Rejects private and reserved IP targets after DNS resolution.
• Uses TLS verification and redirect limits.
• Returns content type and size metadata safely as JSON.

Pre-Send Checklist

• Updated Pre-Send Checklist with a modern production-readiness workflow.
• Expanded content checks for subject line, preheader, personalization, plain-text fallback, footer, unsubscribe, and web version.
• Added accessibility and design review items for alt text, link clarity, mobile rendering, dark mode, and image blocking.
• Added deliverability readiness items for SPF, DKIM, DMARC, sender alignment, suppression hygiene, and test inbox review.
• Added tracking and privacy checks for UTM parameters, consent, analytics, and data minimization.
• Added QA checks for links, landing pages, dynamic content, merge tags, segmentation, and final approval.
• Added post-send monitoring items for bounce rate, complaints, unsubscribes, engagement, and deliverability trends.

Improvements

• Improved Large-template handling across validation modules.
• Improved Line-number accuracy and source-context reporting.
• Improved False-positive reduction for email-client-specific markup.
• Improved Network check performance through sampling, de-duplication, concurrency limits, and hard time budgets.
• Improved Security hardening for external resource checks and submitted HTML processing.
• Improved Validation result wording to better separate hard errors, compatibility warnings, and best-practice guidance.

Highlights

• Added New Email DevTools:
• Inspects emails in a sandboxed iframe with switchable desktop, tablet, and mobile widths.
• Highlights table structures and simulates image blocking to test fallback copy and layout.
• Extracts and displays the first-view preheader content with source context.
• Detects and summarizes Outlook conditional comments and VML usage.
• Flags risky CSS patterns and client-specific pitfalls (e.g., Outlook/Word engine constraints).
• Exposes element attributes, computed styles, and a box-model readout for precise debugging.
• Surfaces accessibility signals (alt, title, role, aria-label) on the selected element.
• Provides in-context optimization hints and one-click copy of the selected node’s HTML.
• Added New HTML Validations and result descriptions for WEB.DE, GMX.DE, and Mail.ru
• Added New CSS Validations and result descriptions for WEB.DE, GMX.DE, Posteo, Zimbra (used by Free.fr), and Mail.ru

Improvements

• Updated Minor performance and security improvements.

Highlights

• Added New email deliverability checks:
• SPF Record Check
• DKIM Record Check
• DMARC Record Check
• MX Records Check
• BIMI Record Check
• rDNS Check
• Blacklist Status Check
• Deliverability Result

• Added New HTML validations and result descriptions, including Unclosed HTML tag(s) detection and a new validation algorithm.
• Added New CSS validations and result descriptions with a new validation algorithm.
• Added New font validations and result descriptions with a new validation algorithm.
• Added New analytics & tracking validation algorithm for deeper analysis including:
• Total Links Count
• Platform Detection
• Tracked & Untracked Links
• Tracking Pixel Detection
• Supported platforms: Mailchimp, Campaign Monitor, SendGrid, HubSpot, Mailjet, MailerLite, ActiveCampaign, Salesforce Marketing Cloud, Google Analytics 4 (UTM)
• Added New mobile validations and result descriptions with a new validation algorithm.
• Added New viewport audit for mobile, tablet, and desktop:
• Image Sharpness Validation
• Text Sizing Validation
• Tap Targets Validation
• Added HTML editor option to export an email's HTML.
• Syntax Highlighting
• Error Highlighting
• Code Formatting
• HTML File Export
• Updated Link validation with a new per-link algorithm.
• Total Links Count
• Unreachable Links Detection
• Insecure Links
• Invalid Links
• Missing Target
• Empty Target
• Missing HREF
• Empty HREF
• Missing Title
• Empty Title
• Updated Image validation with a new per-image algorithm, including:
• Total Images Count
• Unreachable Images Detection
• Insecure Source
• Invalid Source
• Relative URLs
• Missing Alt
• Empty Alt
• Long Alt
• Missing SRC
• Empty SRC
• Missing Width
• Empty Width
• Missing Height
• Empty Height
• W/H Non-Numeric
• Updated Spam validation with a new algorithm for in-depth analysis, including:
• Spam Triggers across words, phrases, structures, symbols/emojis, formatting
• Language Detection
• Link Density Ratio
• Shortened URL Ratio
• Stop-Word Ratio
• Plain Text Size, HTML Size, Total Message Size
• Text-to-Image Ratio
• Supported languages: English, German
• Updated Accessibility validation with new readability snapshot, covering the following language metrics:
• Flesch-Kincaid Reading Ease
• Flesch-Kincaid Grade Level
• Gunning Fog Index
• SMOG Index
• Automated Readability Index
• Updated Pre-Send Checklist → Interactive pre-send checklist with categorized checks.
• Improved Usability & readability of validation results (deep links to HTML editor; simplified categories: error, warning, success).
• Improved Mailserver settings for better deliverability of test emails.
• Improved Core performance & security.
• Updated Email & report export: download validated HTML with PDF report (Beta Version 1.0).
• Discontinued Visual tester and visual tester inspector.