eslint-plugin-mso-email

ESLint plugin for Outlook/HTML email markup: MSO conditional comments, Outlook CSS properties, VML namespaces, and layout table accessibility.

Extracts conditional comments into a virtual file for AST-based rules, and lints full HTML documents for MSO CSS, VML, and table semantics.

Installation

npm install eslint-plugin-mso-email --save-dev

Requires ESLint 9+ (flat config) and Node.js 18+.

Quick Start

// eslint.config.js
import mso from 'eslint-plugin-mso-email';

export default [...mso.configs.recommended];

This lints **/*.html, **/*.amp, and **/*.ampscript files.

VS Code Setup

Configure the ESLint extension to validate HTML:

{
  "eslint.validate": ["html", "javascript"]
}

The MSO Conditional Comments VS Code extension provides overlapping conditional-comment diagnostics without ESLint. Use this plugin for CI and editors with ESLint.

Rules

All rules use the mso/ plugin prefix.

| Rule | Default | Fixable | Description | |---|---|---|---| | mso/valid-mso-condition | error | partial (deterministic typos) | Validate MSO conditional opener syntax | | mso/matching-mso-endif | error | no | Match openers and [endif] closers | | mso/matching-mso-endif-type | warn | yes | Match closer variant to opener style | | mso/no-unknown-mso-property | warn | partial (typo hints) | Disallow unknown mso-* CSS properties | | mso/vml-requires-namespace | warn | yes | Require xmlns:* on html when using VML | | mso/no-unknown-vml-tag | warn | yes | Disallow unknown VML tag names | | mso/no-unknown-vml-attribute | warn | partial (typo hints) | Disallow unknown VML attributes | | mso/table-presentation-role | warn | yes | Require role="presentation" on layout tables |

Fixable legend

| Value | Meaning | |---|---| | yes | ESLint can auto-fix every reported violation for that rule (with default options). | | partial (deterministic typos) | Auto-fix only when the parser returns a single deterministic replacement for the condition substring (for example mos → mso). Invalid operators, unknown versions, and ambiguous conditions are reported without a fix. | | partial (typo hints) | Auto-fix only when the property, tag, or attribute name has a close allowlist match within edit distance. Unknown names with no hint are still reported, but not auto-fixed. | | no | Report only — inserting or removing structural comment markers is unsafe. |

Migration from eslint-plugin-mso-conditionals

// Before
import msoConditionals from 'eslint-plugin-mso-conditionals';

// After
import mso from 'eslint-plugin-mso-email';

Replace rule IDs mso-conditionals/… with mso/….

License

MIT