Workflow Transactional EmailWorkflow Transactional Email

Subject line and preview text

Before anyone opens your email, they see three things in their inbox: who it is from, the subject, and the preview text. Two of those are set on the layout.

Acme Store
Your order #1024 has shipped
Track your parcel - arriving Thursday, no signature needed

The third line is the preview text. Most merchants leave it empty, and the email client then grabs whatever text happens to come first in the email - often "View in browser", an image's alt text, or an unsubscribe line.

Subject

Set on every layout, required. Supports {{ variables.xxx }} and {{ secrets.xxx }}, so you can include the order number or the customer's name:

Your order {{ variables.orderName }} has shipped

Give optional values a fallback so a blank never reaches a customer:

Hi {{ variables.firstName | default: "there" }}, your order is on its way

Keep it under roughly 50 characters if you can - mobile clients truncate beyond that.

Preview text

The Preview text field sits directly under the subject in both the visual builder's General tab and the rich text / HTML editor.

It supports exactly the same Liquid as the subject, so it can carry dynamic detail:

Arriving Thursday - track parcel {{ variables.trackingNumber }}

Aim for 40-100 characters. Clients differ on how much they show; the field caps at 200.

Where it appears

The preview text is added to the email as a hidden block at the very top of the body. Recipients see it in the inbox list, but it is invisible when they open the message - so it never appears twice or interferes with your design.

Behind that hidden block the app adds invisible padding characters. Without them, clients pull the first real text of your email in after your preview line, and merchants end up with inbox entries reading "Track your parcel View in browser Unsubscribe".

Writing a good one

The subject and the preview text are read together, so do not repeat yourself.

Subject Preview text
Weak Your order has shipped Your order has shipped
Better Your order has shipped Arriving Thursday - no signature needed

Add the detail that makes someone open it: the delivery date, the amount, what to do next.

Preview text is not the Description

This one catches people out, so it is worth being explicit.

Field Who sees it What it is for
Subject The recipient The email's subject line
Preview text The recipient The inbox line after the subject
Description Only you, in this app An internal note to tell layouts apart in your list

Description never leaves the app. If you have been writing customer-facing copy there, move it to Preview text.

Checking it

The on-page preview does not show inbox text, because that is the mail client's rendering rather than the email's. To check it:

  1. Use Send test email from the layout.
  2. Look at your inbox list view - do not open the message.
  3. Confirm the line after the subject reads the way you intended.

On a phone, check both the notification and the list, since they truncate differently.

If your preview text contains a variable, remember that a test send uses your Test Variables, not Flow's. See Passing data from Shopify Flow.