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USE CASE Target

Outlook Email Broken Layout Fix: Resolve CSS Flexbox Collapse for eCommerce Campaigns

In eCommerce email marketing, rendering issues directly tank conversion rates and cart recoveries. Product grids, checkout CTAs, and discount banners must display flawlessly to prevent purchase drop-offs. Below is the targeted integration guide to fix CSS Flexbox Collapse inside Outlook 2016 templates when using Mailchimp.

Technical Breakdown

Outlook 2016 uses the Microsoft Word (MSO) which lacks support for standard rendering rules. This causes CSS Flexbox Collapse elements to break or collapse when rendering templates.

Mailchimp Behaviors

Mailchimp's classic template compiler injects custom inline attributes (like 'mc:edit') and automatic CSS reset sheets before delivery. If your fallback code includes head styling wrappers, Mailchimp's post-processing parser will strip media query priorities, breaking display rules in clients like iOS Mail and Gmail. The fallback table structures must have absolute styles inlined directly. Double-check your dynamic product feed blocks. When injecting product loops from your catalog, ensure width sizes are explicitly handled to keep columns from overlapping.

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 Mailchimp campaign manager, make sure you configure your links to run via *|UNSUB|*.

<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 Mailchimp Custom Sandbox

Target Environment: Outlook 2016

How to Deploy inside Mailchimp

1

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

2

Locate your campaign block inside Mailchimp. Drag a 'Code' block into your canvas workspace. Toggle the editor view to Source, paste the optimized code, and click Save.

Targeted Fixes by Use Case & Industry