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Responsive Email

Responsive Email

Responsive emails adapt to different screen sizes (desktop, tablet, mobile). Activator uses MJML under the hood, which handles a lot automatically, but predictable results depend on a few rules.

The core rule: columns stack on mobile

  • Columns inside a Row stack vertically on mobile

  • Each stacked column becomes full-width, regardless of desktop width

This means a 15/15 column layout behaves the same as 50/50 on mobile: both become vertical full-width blocks.

image-20260106-115217.png
Structure
image-20260106-115131.png
Desktop
image-20260106-115150.png
Mobile - As we can see on mobile, the column stretches to the full width of the parent container.



Keep columns side-by-side on mobile (Group container)

Use a Group container when you need columns to stay side-by-side on mobile (e.g., icon + label, price + CTA).

  • Columns directly inside a row: will stack on mobile

  • Columns inside a group: do not stack (they remain in one horizontal group)

Use group containers sparingly; they can reduce readability on small screens if overused.


image-20260106-115404.png
Structure
image-20260106-115416.png
Desktop
image-20260106-115459.png
Mobile



Spacing patterns

Vertical spacing when columns stack

When stacked, sections can become visually cramped. A reliable pattern is a “gap column” that becomes a spacer on mobile.

Example idea:

  • Insert a gap column between content columns

  • Give it 0% width but vertical padding so it acts as a spacer block when stacked


image-20260106-115604.png
Desktop


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Mobile


Horizontal spacing on desktop

Use a gap column with a real percentage width (e.g., 5%) and adjust the content columns so the total is 100%.

image-20260106-115731.png
Configuration
image-20260106-115825.png
Desktop
image-20260106-115837.png
Mobile



Responsive images (fluid on mobile)

If you want an image to:

  • be smaller/fixed on desktop, but

  • expand to full width on mobile

Enable fluid-on-mobile (where your UI exposes it).

image-20260106-115940.png

What to test every time

  • Desktop view: width, alignment, gaps

  • Mobile view: stacking order, spacing, image scaling

  • Links/buttons: tap targets and spacing

  • Outlook-specific rendering (if your org supports Outlook)