It appears your product settings for "Power Popup Plugin" (#997701) still have the Enable Templated Email setting checked with nothing typed in the Email Message field, so there is no default message to send with free links for that product.
When you send a free link for such a product, you would need to enter an Email Message on the Send Free Download Link screen each time. If you leave Enable Templated Email unchecked on the free link screen, the Email Message you type will be added to the link we include; otherwise, if you check Enable Templated Email there, make sure you include the code [%download_link%] somewhere in your template where you want the link inserted.
If you expect to send a lot of free links manually and want to avoid that hassle, we would recommend going through the settings of each product and make sure they all have Enable Templated Email left UN-checked. Then you won't have to type a message every time you send a free link.
You also have a Common Thank-you Email that is only sent once for each actual sale, but not for free links you issue manually. You can customize or delete this message in Seller Admin > Account Preferences. If you want to only send this one message for each sale (rather than a separate message for each product), you can Enable Templated Email in the settings of each product and leave the Email Message field blank to disable the product emails; however, this means you will need to type an Email Message every time you send a free link, as explained above.
This help page explains more about customizing your thank-you email messages:
One other thing I noticed: you appear to be using Redirection for your products, rather than Single File Download. Redirection is not intended for downloads, and we recommend against trying to use it for that purpose, not least because it can cause unpredictable download problems and increases your data-transfer bandwidth usage on your server (which may result in unexpected surcharges or service cut-offs from your host). Even worse, when the buyer's browser is redirected to a product's Redirection URL, that URL is necessarily exposed in the buyer's browser, so they could share that URL with others who could visit it directly to download your file for free without paying first.
When you enable Single File Download in the product's settings, you can upload a file that would be delivered to the buyer through our secure download fulfillment system. Each buyer is issued a unique link that expires after the number of Attempts or (optional) Hours that you define in each product's settings, without ever revealing the "real" location of the file. Our subscription plans starting at $18/mo can also deliver files stored remotely on another server, if you'd prefer not to upload a file to our server. This help page explains in more detail: