Assign Salesforce Users to the MassMailer App
Follow the instructions below to assign the MassMailer App license to the Salesforce users.
1. Access the Salesforce Installed Packages by selecting Setup => App Setup => Installed Packages.
2. On the Installed Packages page, click MassMailer.
3. From the MassMailer page detail page, click Manage Licenses.
4. Click Add Users.
5. Then select each user you want to assign a MassMailer license.