You can define HTML headers and footers to include in your outgoing email messages. At runtime the system puts the HTML header, HTML template text, and HTML footer together as a single HTML document.
The HTML header is placed in the HTML template as the very first line of the html <HEAD> tag. If no <HEAD> tag exists in the template, the header will not be included in the email message even if there is a header defined for the notification event.
The HTML footer is placed as the very last line of the html <BODY> element. If no <BODY> element exists in the template, the footer is not included in the email message even if there is a footer defined for the notification event.
The HTML header, footer, and template rendering occurs before any data element replacements occur. This means that if you have either singular or repeater data elements in either your HTML header or footer these elements are replaced with data at runtime provided that the data elements exist in the result set of the notification event stored procedure.