The subjects look like they are links – they are blue and the mouse pointer turns into a hand.
Examples are “Delivery Status Notification (Failure)”, “Email Feedback Report (Complaint)”, “Undeliverable: [Forum name] Topic name”.
I’ve just noticed that ones in the form “Re: [Forum name] Topic name” do work as links.
I see a bit of this too. Everything is in <a> tags, but some have no href.
I don’t have examples like your first batch, but I think I’d expect those to pop up the email details the way the Rejected list does.
I do have a few “Re: [Forum name] Topic name” that don’t link to anything because that topic has been deleted.
At the least, it would be nice if items with no link destination weren’t rendered as links.
I slipped this across to UX. I think these should not be styled like links unless there is something for them to link to.
On my personal site, I can see that some of them do link to posts as expected, but most do not even though they are styled as links.
Looks like this has been addressed over here: