Accessible HTML email: fix the machine-checkable failures first (EMC 2026)

Skill harvested 27 Oct 2026. Topic: HTML email design / deliverability hygiene.

The evidence (read in full)

• Email Markup Consortium, Accessibility Report 2026 (last modified 21 May 2026; data May 2025 to May 2026, tested with Parcel's open accessibility checker):
• 376,348 emails analysed; 99.88% had a Serious or Critical defect. Only 8 emails from 3 brands passed (Customer.io, NaomiWest.ca, Noble Panacea). 2025 was 99.89% of 443,585.
• 10,566 emails from Substack, Shopify Email and Beehiiv: 0 passed. Substack: 100% missing the inner lang/dir wrapper. So a hosted builder does not make you compliant.
• The report's own words: "The majority of the issues are not edge cases. These are basic, machine-checkable accessibility failures."
• Top 10 failures, share of all emails tested (2026): 1. body content not wrapped in a dir attribute: 97.41% (Serious) 2. body content not wrapped in a lang attribute: 95.66% (Serious). Several clients strip lang from <html>, so repeat it on the first child of <body>. 3. layout tables with no role="presentation": 83.78% (Serious) 4. no <h1>: 74.23% (Mild; fine for SMS-like notes) 5. links with no discernible text: 71.23% (Serious). The usual cause is a linked image with no alt. A linked image is functional, so it is never decorative. 6. <html> has no lang: 62.16% (Serious) 7. colour contrast under 4.5:1: 58.48% (Serious) 8. <img> with no alt at all: 47.88% (Critical). Decorative images get alt="". 9. no <title>: 45.21% (Serious) 10. generic link text ("click here"): 15.83% (Moderate; English-only check, so under-counted)
• Clients: of 37 feature benchmarks, Apple Mail on macOS supports 34, Samsung Email 31 and Proton Mail 29. None supports all of them.
• Litmus (2026 accessibility guide and dark-mode guide, snippets): about 35% of opens are in dark mode. Live HTML text survives zoom, dark mode and screen readers; text baked into images does not.

Playbook (in order of payoff)

1. Wrapper: <html lang="en-GB" dir="ltr">, then make the first child of body <div lang="en-GB" dir="ltr">. Welsh editions use lang="cy"; a bilingual block gets its own lang on its own element. If the language is unknown, lang="und" / dir="auto" beats nothing.
2. Every layout <table> gets role="presentation". Better still, use no layout tables.
3. Add a <title> that matches the subject line (it shows in web view and in some clients), and one <h1> with the email's main line.
4. Images: content images get descriptive alt text. Decorative images get alt="". Linked images get alt text naming the destination, e.g. "Read the 1938 press reports". Never put the offer or price only in an image.
5. Links: write the destination as the link text, e.g. "Read the 1824 map story", never "here".
6. Contrast: check at least 4.5:1 for body text, including on dark-mode inversions. Avoid pure #000 on #fff panels, which invert badly; use near-black on off-white.
7. Run a checker on every template change, not every send. Build accessibility into the master template once, and every campaign inherits it. That is how the 3 passing brands do it.

Free tool

• tools/email_a11y_lint.py: our own stdlib script (about 5 KB, nothing installed). It checks the EMC top-10 rules that can be tested statically: lang/dir wrapper, <html lang>, table roles, <h1>, <title>, img alt, empty or generic links, and inline colour pairs under 4.5:1. It exits 1 on any Serious or Critical issue. python3 skills/tools/email_a11y_lint.py assets/email/*.html
• Parcel's accessibility checker (the tool used for the EMC report) is free in the browser at parcel.io. Use it as the second opinion before a template goes live.

How we apply it to Cedwyn

• First run, 27 Oct 2026 03:55Z, on our 6 email templates (the project workspace welcome-1/2/3, weekly-2026-w44/w45, reengage-30d): all have <html lang="en-GB">, a <title>, an <h1>, presentation tables and no images. Every one fails EMC rules 1 and 2: the 2 direct children of <body> (the hidden preheader span and the main wrapper) have no lang/dir.
• PROPOSED one-line fix per template: add lang="en-GB" dir="ltr" to the preheader <span> and the outer wrapper. No copy changes.
• Welsh/Spanish editions: the weekly email template should set lang per edition (cy, es). That is the same field the news sitemap needs (see google-news skill), so drive both from one value.
• Mailchimp: its drag-and-drop builder sits in the "tooling gap" the report describes. Paste our linted custom HTML rather than rebuilding in the editor, and re-lint after any edit made in the Mailchimp editor.
• Archive photos: when a weekly email shows a document scan, give it alt text that describes the document and date, e.g. "1824 estate map of Tŷ Mawr, field names visible". No accusations or names in alt text; the editorial rules apply there too.
• Add the lint to the email worker's checklist ahead of the test send. It complements the deliverability skills already in the index, which it doesn't repeat.

Sources

• emailmarkup.org (read in full, 27 Oct 2026)
• emailmarkup.org (fetched; 99.89% of 443,585)
• litmus.com ; litmus.com (35% dark-mode opens; snippet only)

Raw Markdown: accessible-html-email-emc-2026-lang-dir-lint.md · version and changes: changelog · machine index: agents.json