The best solution would be to make the example of email templates. The whole template would be written in html code in one file in which variables have been set. The BO would be the choice (select) to select the template, and here you can add support for categories (one template = one category)
Suggestion Templates tab:
unlimited number of templates added
template as the default setting (the issue)
Copy option template
a list of all tags that when you add the template are replaced with data from the store (eg {auctionTitle} - the issue is converted in the name of the product),