I haven't found a good way to obtain the category/categories for a content pice so far. The closest that takes you there is indeed tracing along the ancestors and checking the node type for each of the ancestor: https://community.lithium.com/t5/Developers-Discussion/Get-ID-of-current-category/m-p/125151
Which does not work too well in the email template Velocity environment :(
${notification.message}
might return a message context object like documented in https://freemarker-docs-portal.lithium.com/refer/contextObjects#message but even that won't bring you far in obtaining the category.
Maybe you can work around by hiding the category in some short / long description field of the board (depending on whether you not surface this description somewhere in your community UI)?
The category description is an interesting idea, but we do display these elsewhere in the community. I also didn't see a context object for it. :catsad:
