It is possible to import an external mailing list, in either a .txt or .csv format; however, you cannot use the Update Statistics feature since the list data lacks any association to existing Salesforce Leads or Contacts. Mailing lists created from Leads & Contacts, or a Salesforce Campaign, include a Salesforce record ID. This data is missing from any list created from an external file. To create a list from an external file follow these steps.
- Login to your Salesforce account
- Click New List
- Select the Import an External Mailing List option
- Follow the steps to complete the import