Email blocks in Campaign Agent

This article explains how Campaign Agent builds and manages your email block library, how to import and update blocks, and how to fix common block issues.

Campaign Agent doesn't generate email designs or images from scratch. Instead, it reuses blocks from your existing email designs — assembling and personalizing them for each new campaign. The quality of your output depends on the quality of your existing blocks.

How Campaign Agent builds your block library

The first time you open Campaign Agent in a project, it automatically scans your existing email campaigns in the background. You can start using Campaign Agent immediately while the scan runs.

Campaign Agent looks through lifecycle campaigns triggered by event or repeat, and tries to capture at least one version of each of the 11 block types it recognizes:

• header, footer, hero banner
• product grid, product detail listing, single product spotlight
• heading, text block, image, CTA button, spacer

For each candidate email, Campaign Agent:

1. Identifies the base email template — global styles, font imports, the main content area, and background definitions.
2. Slices the email body into individual blocks.
3. Identifies each block's purpose — its type and description.
4. Marks editable elements with parameters so they can be modified in the editor.
5. Collapses product grids into a repeatable product card.
6. Tests each block against the base template for style compatibility.
7. Saves approved blocks to Asset Manager with the [CAMPAIGN AGENT] prefix.

The scan continues until it has enough distinct blocks or has reviewed around 20 campaigns. The time it takes depends on the size and complexity of your email library. Campaign Agent tries to remove near-identical duplicates, but some may still appear.

If a block type isn't found, Campaign Agent uses built-in default blocks so emails still look complete. Once a custom block of a given type exists in your library, the default for that type is no longer used.

Manage your block library

You can add or update blocks in two ways.

Import a full email design

Pick an existing email template from Asset Manager or paste raw HTML. Campaign Agent runs the same process as the automatic scan — identifying block types, marking editable elements with parameters, and saving blocks with the [CAMPAIGN AGENT] prefix.

This option replaces all previously saved blocks and the base template and can't be undone automatically. You can only undo this manually in Asset Manager by restoring the previous base template and blocks.

Use this when your existing design is outdated and you want to replace the entire block library.

Import individual blocks

Import a single block from Asset Manager as a custom row. This adds the block to your library without replacing existing blocks.

When you import a block, Campaign Agent generates a preview for a test customer and analyzes the resulting HTML to identify the block type, editable elements, links, images, styles, and repeatable rows and columns. The block is saved with the [CAMPAIGN AGENT] prefix and appears in the block picker.

Use this when a specific block type is missing from your library and you want to add it without affecting existing blocks.

Common block issues

The following issues can occur after the automatic scan or after importing blocks manually. For most issues, re-importing the block resolves the problem. If it doesn't, edit the block parameters directly in Asset Manager.

Fix blocks manually in Asset Manager

If re-importing a block doesn't resolve the issue, you can edit the block directly in Asset Manager.

Campaign Agent blocks are stored as custom HTML blocks with the [CAMPAIGN AGENT] prefix. Each block contains parameters — markers that tell Campaign Agent which elements can be edited and how.

When Campaign Agent scans or imports a block, it:

• Takes a visual snapshot of the block rendered for a test customer. It doesn't carry over the block's original Jinja logic — some custom logic, such as conditional column counts or conditional layouts, is lost.
• Marks editable elements with parameters.
• Detects system links — {{ consent.page }}, {{ email.view }}, {{ email.unsubscribe }} — and implements them using standard defaults. To change the default behavior, update the block description or the parameter value.

Each block also has a description and parameter descriptions that instruct Campaign Agent on how to use it — for example, "max 20 characters" or "recommended for at most 3 rows of products."

For product grids, include the maximum column count in the block description — for example, "Max. 2 columns" — otherwise Campaign Agent may exceed the layout limit.

To fix and test a block:

1. Find the block in Asset Manager — look for custom blocks with the [CAMPAIGN AGENT] prefix.
2. Edit the block parameters. For parameter syntax and reference, see Email block parameters in Campaign Agent.
3. Save the block.
4. Add the updated block manually to an email in Campaign Agent to verify it renders correctly and is editable.
5. For product blocks, ask Campaign Agent to display products — for example: "Show bestsellers in this block" — to confirm the block behaves as expected.