The mailing list will be organized in a central repository(database). Database with 50 + columns.
Identify a unique key to identify individual records and Upload your list to the database.
Update the existing records using subsequent uploads.
Build a dynamic query to download certain certain of records.
Custom Version - Software as a Service
The custom version will have all the capabilities of the basic version and any custom database additions (new columns), functions(to do certain things before insert or download) and Interface (building dynamic query).
The customization is done for you specific requirement at a reasonable additional cost.