Outlook Email Broken Layout Fix: Resolve CSS Flexbox Collapse for Client Rendering Engine Anomalies
Email client rendering variations are caused by differences in parser engines. Legacy Outlook engines ignore modern block models, forcing layouts to stack vertically. Below is the targeted integration guide to fix CSS Flexbox Collapse inside Outlook 2013 templates when using ActiveCampaign.
Technical Breakdown
Outlook 2013 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.
ActiveCampaign Behaviors
ActiveCampaign's editor parses HTML template imports and automatically cleans inline attributes, which can break VML tags. Always use absolute styles and avoid relying on classes. Test layout code regressions side-by-side using the Campaign Diff Comparator before pushing visual style changes to your production templates.
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 ActiveCampaign campaign manager, make sure you configure your links to run via %UNSUBSCRIBELINK%.
<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
How to Deploy inside ActiveCampaign
Copy the fixed VML or table wrapper code block from the remediation box above.
Insert an 'HTML block' from the layout builder panels. Avoid standard text boxes, as the ActiveCampaign parser might strip conditional MSO comment strings on saving.