Hey UX community!
In this profession, we are always trying to learn more about our users and their interactions with our products. Whether it be a usability test, survey, or card sort, having a list of willing customers that you can grab into is always necessary.
My question: How do you maintain your list of current customers that have opted into user research activities? Do you keep an Excel spreadsheet, maybe a Wiki page, or possible an email list. I'd like to hear your process!