app/code/Magento/Email/README.md
Magento_Email module enables you to manage email templates.
This module adds the page to create/edit email template at the admin side and possibility add/update templates programmatically.
This module is one of the base modules. You cannot disable or uninstall this module.
For information about a module installation, see Enable or disable modules.
Extension developers can interact with the Magento_Email module. For more information about the extension mechanism, see Plugins.
The dependency injection mechanism enables you to override the functionality of the Magento_Email module.
The module introduces layout handles in the view/adminhtml/layout directory.
For more information about a layout, see the Layout documentation.
You can extend product and category updates using the configuration files located in the view/adminhtml/ui_component directory.
For information about a UI component, see Overview of UI components.
For information about significant changes in patch releases, see Release information.
More information about email templates are at articles: