The Salesforce Email Template Builder uses a drag-and-drop canvas powered by a FlexiPage architecture. This underlying structure is only generated when a template is created as a new Lightning Email Template specifically designed for the builder.
Email templates that were previously created using the Classic editor, the standard Lightning email editor, or migrated from a legacy system (such as TargetX) do not have this FlexiPage structure. As a result, the "Edit in Builder" button will not appear on these templates, and the drag-and-drop canvas cannot be loaded for them.
This issue commonly affects organizations migrating from older email systems to Education Cloud or Sales Cloud, where legacy templates are carried over but cannot be upgraded in place.
Symptoms:
Pre-existing email templates cannot be converted or upgraded to use the Email Template Builder. Salesforce does not allow the underlying template type to be changed after creation.
To access the Email Template Builder for your email designs:
Note: You will need to manually recreate your legacy template designs in the new builder framework. Text and images can be copied and pasted into the new drag-and-drop components. Once templates are built in the new framework, all team members with access will be able to use the builder for future edits.
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