MSO Conditional Comments — VS Code Extension

IntelliSense for MSO (Outlook) conditional comments in HTML email — hover translations, completions, and inline diagnostics.

Features

Hover translations

Hover over any MSO conditional comment to see a plain-English translation of its condition.

<!--[if gte mso 14]>

Hovering shows: MSO Conditional — Visible to: Outlook 2010 and later (MSO ≥ 14)

Inline diagnostics

Errors and warnings appear directly in the editor without requiring an ESLint setup:

Diagnostic	Severity	Example
Invalid condition syntax	Error	`<!--[if mos 16]>` — typo in keyword
Unknown operator	Error	`<!--[if newer mso 16]>` — `newer` is not valid
Unknown version	Error	`<!--[if gte mso 13]>` — version 13 does not exist
Opener without closer	Warning	`<!--[if mso]>` with no matching `<![endif]-->`
Closer without opener	Warning	`<![endif]-->` with no preceding opener

Completions

Type <!--[if or <![if to trigger snippet completions for the most common MSO conditional patterns:

Trigger	Description
`mso-all`	Target all Outlook versions
`mso-gte`	Target Outlook greater than or equal to a version
`mso-not`	Hide from all Outlook versions
`mso-hidden-start`	Downlevel-hidden block — hidden from Outlook
`mso-hidden-end`	Close a downlevel-hidden block

Supported file types

HTML, AMP, SSJS, AMPscript, and Handlebars files (any file VS Code identifies as html, ampscript, sfmc, ssjs, or handlebars).

Settings

Setting	Type	Default	Description
`msoConditionals.diagnostics.enable`	boolean	`true`	Show inline errors and warnings. Disable if you prefer diagnostics from `eslint-plugin-mso-email` instead.

Valid Outlook versions

MSO version	Outlook product
9	Outlook 2000
10	Outlook 2002
11	Outlook 2003
12	Outlook 2007
14	Outlook 2010
15	Outlook 2013
16	Outlook 2016, 2019, and 365

Valid operators

Operator	Meaning
`gte`	greater than or equal
`gt`	greater than
`lte`	less than or equal
`lt`	less than
`eq`	equal

Companion tools

eslint-plugin-mso-email — lint MSO conditionals, MSO CSS, VML, and layout tables in CI or in editors without this extension.
mso-conditional-parser — the underlying parser, usable as a standalone npm package.

Telemetry

This extension sends anonymous usage telemetry to help prioritise improvements. It records only:

Activation — that the extension started, plus which known SFMC-related extensions are installed alongside it (booleans only).
Diagnostics usage — how many times MSO diagnostics ran and the total number of diagnostics produced (counts only — never your file contents, comments, or any identifiers). This aggregate is sent at most every five minutes, and once more on shutdown if a non-empty aggregate remains.

No personally identifiable information, file contents, or credentials are ever collected. Events are anonymous (keyed by VS Code's stable, non-PII machine id) and sent to a PostHog project hosted in the EU. The full event catalogue is in telemetry.json.

Telemetry is governed solely by VS Code's global telemetry setting. To opt out, set telemetry.telemetryLevel to off in your settings — the extension checks this before every send and stops immediately when it changes.

License

MIT

MSO Conditional Comments

Jörn Berkefeld