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USE CASE Target

Fix CSS Flexbox Collapse in Apple Mail (Desktop) — Salesforce Marketing Cloud (SFMC) Guide for Editorial & Content Newsletters

Editorial newsletters rely on content layout readability and structural text spacing. If fonts default to Times New Roman or layout borders break, subscriber engagement metrics suffer. Below is the targeted integration guide to fix CSS Flexbox Collapse inside Apple Mail (Desktop) templates when using Salesforce Marketing Cloud (SFMC).

Technical Breakdown

Apple Mail (Desktop) uses the WebKit which lacks support for standard rendering rules. This causes CSS Flexbox Collapse elements to break or collapse when rendering templates.

Salesforce Marketing Cloud (SFMC) Behaviors

SFMC's Content Builder wraps block exports in div frames that can break conditional comments. Additionally, AMPScript calls for personalizations can trigger parsing errors if they are inside MSO conditional comments. Ensure your AMPScript tags are evaluated *outside* the VML blocks. Keep your editorial body clean. Strip redundant CSS class definitions using Vaporize to ensure the newsletter stays under Gmail's 102KB clipping ceiling.

Remediation Code Block

To resolve this, modern layouts must be compiled down to Outlook-compliant nested HTML table models. Each flex container becomes a table row, and each flex child becomes a table data cell (td) with explicit pixel or percentage widths. In your Salesforce Marketing Cloud (SFMC) campaign manager, make sure you configure your links to run via %%unsubscribe_url%%.

<table role="presentation" border="0" cellpadding="0" cellspacing="0" width="100%">
  <tr>
    <td width="50%" valign="top" style="padding: 20px;">Column 1</td>
    <td width="50%" valign="top" style="padding: 20px;">Column 2</td>
  </tr>
</table>

Live Code Sandbox Test

Interactive Salesforce Marketing Cloud (SFMC) Custom Sandbox

Target Environment: Apple Mail (Desktop)

How to Deploy inside Salesforce Marketing Cloud (SFMC)

1

Copy the fixed VML or table wrapper code block from the remediation box above.

2

Create an 'HTML content' layout block in Content Builder. Paste the table structure. Enclose any custom merge tags inside standard AMPscript wrapper lines.

Targeted Fixes by Use Case & Industry