I'm not certain that this would be a justifiable core option, but maybe something that could be implemented in a standalone extension or w/in the Pretty Mail extension.
I run a forum for a client that is highly conscious of any security risks. We are tightening down our forum as much as possible. In doing so, I noticed that many of the notification emails sent by Flarum include not only the link to the discussion, but also the content of the post that is being linked. Seeing as these posts are set to be only visible to users that are logged in, we'd like to not be sending the content to people's email inboxes. An option to exclude the post content from email notifications and only provide a link to the post would be a great addition. Otherwise, our only other alternative is to not allow notifications via email. However, this would likely drop engagement of our users.
I've not seen that this has been considered in the past (here nor on Github). Thoughts?