It is important to understand the difference between a data source and mailing list.

Data Sources

A data source can be can be a file upload or live data feed that supplies the data that is displayed in eInsight CRM. Examples include data from a PMS, web forms and loyalty programs. Multiple profiles for the same individual can be combined from different data sources. 

Mailing Lists

Email addresses are either opted into or opted out of mailing lists. The opt-in/opt-out preference for each list is carried over to all profiles associated with the email address, regardless of the data source of the profile. You must have a Subscription Center enabled in order to create mailing lists.