In a different article we described how you can create your own queue and send personalized messages to your users.
To make it more simple, you can include a questionnaire link to one of your newsletters or public messages via any channel and get the feedback you are looking for.
Simply follow the Public Link instructions to get your questionnaire link, either long or short, depending on the channel you are planning on using.
Now you can setup your message and embed the url like the following examples:
SMS
Thank you for your purchase! Take 30 seconds to tell us your opinion here: %{public_link}
Where %{public_link} will be replaced with the url.
Somewhere inside the HTML of the email, you can add a button with the following link:
<a href="%{public_link}">Take the Survey!</a>
Where %{public_link} will be replaced with the url.