Check email accessibility and compatibility

What are Compliance checks?

A well-designed email can still fail the people who receive it. Some recipients use screen readers or other assistive technologies, and the same email can render differently across email clients such as Gmail, Outlook, and Apple Mail.

Compliance checks help you find these problems before you send. The Compliance panel runs two checks against your email's HTML:

• Accessibility checks your email against the Web Content Accessibility Guidelines (WCAG), so you can improve usability for everyone, including people using assistive technologies.
• Compatibility checks how each element of your email renders across email clients and devices.

Accessibility and compatibility solve different problems. Accessibility makes sure your email can be used by all recipients; compatibility makes sure it displays correctly everywhere. An email can pass one check and fail the other, so be sure to check both.

Both checks run on the same HTML and update automatically when the email loads.

Open the Compliance panel

You can run Compliance checks on a received email or on a design you are building.

To check a received email:

1. Select Inboxes from the main menu, and open one of your inboxes.
2. Open the email you want to check.
3. In the email viewer toolbar, select Compliance.

To check a design:

1. Navigate to the Designer via the main menu.
2. Open the design you want to check.
3. In the toolbar, select Compliance.

The Compliance panel opens with an Accessibility section and a Compatibility section.

Accessibility checks

What Mailosaur checks

Mailosaur checks your email against WCAG 2.2 to level AA. Level AA is the benchmark most organisations use for legal and practical accessibility compliance. (WCAG defines three levels: A is the minimum baseline, AA is the common standard, and AAA is the strictest.)

WCAG groups its guidelines under four principles. Your email should be:

• Perceivable — recipients can see or hear the content. For example, images have alternative (alt) text, and text has sufficient colour contrast.
• Operable — recipients can navigate and use the content, including with a keyboard rather than a mouse.
• Understandable — the content is clear and predictable, with a defined language and meaningful link text.
• Robust — the content works across devices and assistive technologies, with valid, well-structured HTML.

Read the accessibility results

The Accessibility section summarises your results and shows the percentage of checks your email passes. Results are grouped into three colour-coded tabs:

• Passed (green) — checks your email meets.
• Inconclusive (amber) — checks that need a manual review, because they cannot be verified automatically.
• Failed (red) — checks your email does not meet.

Each failed or inconclusive check shows an impact level — Critical, Serious, Moderate, or Minor — which ranks issues by severity. Expand a check to see a description, a link to the relevant WCAG criterion, and the affected elements in your HTML.

Fix an accessibility issue

1. Expand a failed check in the Accessibility section.
2. Review the affected HTML elements listed under the check.
3. Update your email's HTML to resolve the issue.
4. Reload the email or design to re-run the check.

Common fixes include:

• Adding alt text to images
• Using descriptive link text instead of vague phrases such as "click here"
• Increasing colour contrast between text and its background
• Using a correct, ordered HTML heading structure

If you are unsure how to resolve a check, use its link to the WCAG criterion. The linked guidance explains why the issue matters and how to fix it correctly.

Compatibility checks

What Mailosaur checks

Mailosaur renders each element of your email against 90+ email clients, including Gmail, Outlook, and Apple Mail, and reports how widely each element is supported. Here, an element means an HTML element or CSS rule used in your email. This helps you find layout and styling that works in one client but breaks in another.

Read the compatibility results

The Compatibility section groups results into three colour-coded tabs:

• Compatible (green) — the element displays as it was designed to in every client tested.
• Partial (amber) — the element renders with minor differences in some clients.
• Incompatible (red) — the element fails to display correctly in at least one major client.

Expand an element to see a description, a per-client support breakdown by platform and version, and the occurrences of that element in your email's HTML. The per-client breakdown shows exactly which clients are affected, so you can judge the impact for your own audience.

Common use cases

• Marketing email QA — validate campaigns before sending to improve reach and reduce accessibility complaints.
• Accessibility compliance — align emails with WCAG standards and prepare for audits or internal policy reviews.
• Cross-client confidence — confirm that your email renders correctly across the clients your recipients use.