Includes are reusable pieces of content that you can use throughout your templates and email campaigns.
The most common use of an include is to create a standard header or footer. If you create a header once and include it in multiple templates, you will only have to make changes in one place later.
Click on the Includes tab and create an include. You must give the include a name, and an HTML version and a Text version.
Use the following syntax:
{include "includename"}
Depending on whether you are in HTML or Text mode, the correct version will be included.
You may not do an include within another include.
For performance reasons, the include syntax is not dynamically evaluated; therefore you cannot, for example, do {include user_preference_setting}. As a workaround, you could wrap your include in a conditional:
{if user_preference_setting == 'redlayout'}
{include "redlayout"}
{/if}