scorpio54378638, I have not been deleting any post whether they ask the same question or not.
there is no support in Power Messenger for importing a prior mailing list. Power Messenger can be used without prior coding knowledge if you are using supported features of the product, The User Registration page.
Trying to import an existing mailing list, however, is not one of those supported features, therefore requires some coding knowledge.
You can import a csv file to the Power Messenger database using one of the MySQL GUI Tools like PHPMyAdmin, SQLYog or Sequel Pro.
at a minimum, you will need to import the users email address and password to the users table.