A set of questions about a topic that’s used for research purposes. Questionnaires are commonly used in digital marketing to get feedback on user experience (UX). For example, you might send one after a customer makes a purchase to find out if they experienced any confusion during the checkout process. Marketers also commonly use questionnaires after someone unsubscribes from a newsletter or other mailing list.

Combining Email Marketing with Other Types of Marketing
Whether you choose to do your marketing online or offline, one thing does not change. This is the concept that no single marketing strategy will be as effective as a combination of two or more marketing strategies.