> This page is part of the [Customer.io documentation](https://docs.customer.io). For the complete index, see [llms.txt](https://docs.customer.io/llms.txt).
> Last updated: July 10, 2026

# Support Microsoft Office with MSO syntax

[BetaThis feature is new and we're actively working on it.](/accounts/settings/beta-experimental-features/#beta-features)

The code editor in Design Studio includes tools to help you write and manage Microsoft Office (MSO) syntax so your messages render more consistently in Outlook.

## Add conditional logic for Outlook

You can add conditional logic that’s only parsed by Outlook through [MSO comments](https://stackoverflow.design/email/base/mso/).

### Syntax highlighting

We visually distinguish MSO comments from regular comments to help you scan your email.

For example, the following comment:

```html
<!--[if true]>
<table role="presentation" width="100%" align="center" style="background:#EEE">
    <tr>
    <td></td>
    <td style="width:600px;background:#ffffff;padding:24px;">
<![endif]-->
```

becomes

[![mso-syntax-highlight.png](https://docs.customer.io/images/mso-syntax-highlight.png)](#7c6f5249c3a7765ac0e897e5382838c2-lightbox)

### Disable syntax highlighting

You can disable syntax highlighting for MSO comments in your editor preferences. Click `Cmd/Ctrl` + `,` then turn off the toggle. MSO comments will then show in grayscale instead.

## Auto-complete MSO properties

In the code editor, type `mso` within a custom CSS property or style attribute and you’ll see a list of MSO CSS properties. Type until you find the one you want or scroll through the list. Then press **Enter** to auto-complete the property name.

*   *   [Add conditional logic for Outlook](#add-conditional-logic-for-outlook)
        *   [Syntax highlighting](#syntax-highlighting)
        *   [Disable syntax highlighting](#disable-syntax-highlighting)
    *   [Auto-complete MSO properties](#auto-complete-mso-properties)

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