So, we have products with downloadable items.
Can we add a link to them in the e-mail (order e-mail) or is this impossible?

AFAIK you are limited to the predefined Tokens.
The only way (I know) to download the file is by going to your order history.

You can see a listing of all of the available e-mail tokens in the documentation below:

https://hotcakescommerce...3-E-Mail-Template-Tokens 

In short, you can't display the download link in an e-mail easily, unless you choose to override the e-mail task in your own custom order workflow task. Documentation on custom workflows is below:

https://hotcakescommerce...Order-Workflow-Solution- 

Then, you'd implement something like this, but inject the download link:

https://hotcakescommerce...stomers-Programmatically 

In closing, I'd like to say that we'd suggest against this approach since you lose the huge opportunity of additional branding, upsell/resell, value proposition, privacy/security, and analytics that you get by simply redirecting the customer back to your website to view and click on the download link. In general, it's always a best practice to keep sending your customers and prospective customers to your website for everything that you can.

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