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.com Leads or Contacts. Mailing lists created from Leads & Contacts, or a Salesforce.com Campaign, include a Salesforce.com 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.com account
- Click New List
- Select the Import an External Mailing List option
- Follow the steps to complete the import