Marketo allows you to set the maximum number of people that can qualify for a smart campaign; this helps you avoid accidentally emailing your whole database. If you want to override this limit, here’s how.
Be sure to enable person restrictions for smart campaigns in Marketo Admin.
In Marketing Activities, go to your smart campaign and click Schedule.
In Smart Campaign Settings, click Edit.
The default limit is the one set in Admin.
Enter a new limit and then click Save.
The smart campaign will not run if the number of people who qualify exceed the set limit.
Be careful with this feature so that you do not accidentally include too many people.