With a contact list, or panel, you can distribute survey invitations. You can either create a contact list in Qualtrics or import contacts from an external file or a survey.
When you use a contact list please store as little personal data in the list as necessary. A contact in Qualtrics should contain at least an email address. This means you can keep any other personal data in a separate – well protected – file outside Qualtrics.
The ExternalDataReference field in a contact list can be used to store pseudonyms like Respondent ID’s. These ID’s can also be embedded in the survey data.