Which of the following is NOT a feature of Email Programs?

The feature that is not associated with Email Programs is the ability to run multiple tests simultaneously. Email Programs in Marketo are designed primarily for executing and managing email campaigns, and they usually allow for a single testing variant (like A/B testing) within a campaign at a time. This means that if you want to conduct different tests, you would typically do so across separate Email Programs or campaigns instead of concurrently within the same program, making the management of such email campaigns simpler and more focused on one variant at a time.

On the other hand, the features that were presented in the options — like the inability to re-send (which is a characteristic feature of Email Programs; they are not designed for re-sending once an email has been sent), the Head Start feature which helps in planning and optimizing the email send process, and A/B testing capability which allows marketers to compare the performance of different email variants — are all integral to the functionality of Email Programs in Marketo.