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Fix Outlook Button Border Collapsing in Yahoo Mail — Brevo (Sendinblue) Guide

A programmatic integration guide for resolving email rendering crashes inside Yahoo Mail using Brevo (Sendinblue)'s layout editor environment.

Root Bug Analysis

Yahoo Mail uses the WebKit / Blink Web Wrapper which lacks support for standard rendering rules. This causes Outlook Button Border Collapsing elements to break or collapse when rendering templates.

Active rendering engine: WebKit / Blink Web Wrapper

Brevo (Sendinblue) Specific Guide

Brevo (Sendinblue)'s delivery wrapper can clean and restructure elements during import, creating dynamic spacing differences inside Yahoo Mail.

Integration Step:

Open Brevo's template canvas, select the element you wish to configure, click 'Edit HTML' or insert a standalone 'HTML' content block, and paste the code.

ESP Unsubscribe Alignment

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

Brevo (Sendinblue) Unsubscribe Tag:{{ unsubscribe }}

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 Yahoo Mail when templates are sent from Brevo (Sendinblue).

Interactive Brevo (Sendinblue) Custom Sandbox

Target Environment: Yahoo Mail

Auto-compile fixes inside RenderOps Workspace

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

Launch VML Button Builder

Fix Outlook Button Border Collapsing on Other clients for Brevo (Sendinblue)