These messages contain by default orange lines and the text "Workflow Notification". These lines and text are created with templates and can be modified to match the e-mail template of your organization.
The templates can be modified on site level, site collection level or farm wide.
Go to the Site Actions and select at the Nintex Workflow Section the option Message templates.
The messages are built from three templates:
- Notification Header
- Approval Required Notification / Approval No Longer Required Notification
- Notification Footer
When you click in one of the template blocks the Editing Tools come available in the tool-bar and the template can be modified.