You can do this using a JSS process trigger. Please add a process trigger with the following settings:
Events: Download file
Type: JSS script
Script:
var isShareDownload = event.virtualPath.indexOf("/Share/")==0;
if (isShareDownload && event.ownerEmail) {
mail.smtp.server = "smtp.gmail.com";
mail.smtp.port = 587;
mail.smtp.userName = "my.account@gmail.com";
mail.smtp.password = "my.password";
mail.smtp.enableSSL = true;
var message = event.windowsFileName + " was downloaded";
mail.send("sender@test.com", event.ownerEmail, "Shared file downloaded", message);
}
Leave the rest of the settings as is. Make sure you set the SMTP server details as appropriate and replace sender@test.com
with your sending email address. You must also set the email address property of each user to whom you'd like notifications sent.