I think it’s a little too miss-able, but it’s hard to know without testing it (i.e., having my users complain ). It certainly fits in with Discourse’s existing design.
Basecamp just lists them in gray next to the reply link. I’d actually like something a bit more obvious, but maybe this is sufficient. I’m sure they’ve tested this (in their somewhat different context). I think it’s worth trying and seeing what happens. I’d like to test both of these, but we’re a small group and the users who are likely to give me feedback are even smaller.
Following @DeanMarkTaylor, in both cases, we’d also need to fix how many users to list by name if they exceed X in total. In the email this might look like (with a limit of 5 users):
“Replies to this message will be sent to: Howard Shay, Asuncion Lukowski, Darell McChristian, Belia Graney, Tammi Sato and 7 other users.”
Not sure how the visible users would be chosen, nor how many they should be. Maybe by OP + recent activity, or is that overthinking this?