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How to Fix Outlook Button Border Collapsing in Outlook 2016
for Mailchimp Campaigns

A programmatic integration guide for resolving email rendering crashes inside Outlook 2016 using Mailchimp's layout editor environment.

Root Bug Analysis

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

Active rendering engine: Microsoft Word (MSO)

Mailchimp Specific Guide

Mailchimp's delivery wrapper can clean and restructure elements during import, creating dynamic spacing differences inside Outlook 2016.

Integration Step:

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.

ESP Unsubscribe Alignment

When compiling custom HTML templates for Mailchimp, you must ensure your layout retains deliverability compliance loops. Mailchimp requires you to insert their specific unsubscribe merge tag, otherwise your campaign delivery will be flagged by automated spam audits.

Mailchimp Unsubscribe Tag:*|UNSUB|*

Documented Client Behavior

Expected layout behavior based on target rendering engine specifications:

Documented behavior: Outlook Button Border Collapsing causes elements to stack vertically or clip in Outlook 2016 when templates are sent from Mailchimp.

Interactive Mailchimp Custom Sandbox

Target Environment: Outlook 2016

Auto-compile fixes inside RenderOps Workspace

Load layout code directly into our VML Button Builder to compile responsive table frameworks that display cleanly in Outlook 2016.

Launch VML Button Builder

Fix Outlook Button Border Collapsing on Other clients for Mailchimp