Hi,
Sorry I missed this. It was posted in the general forum, so I've now moved it to the correct forum and can answer your question.
It's not a bug as such. What's happening is that when someone sends you a message and then their account is deleted or banned, all of their content is removed along with the account.
The issue with messages is that they're also linked to the active account of the person who received the message. Because of that, the message can still appear in your inbox, but when you try to open it, the actual content has already been removed because the sender's account no longer exists. That's why you see the standard "Item not found" message that appears when content is no longer available.
I do think we could improve this by removing those messages from the inbox completely when the sender's account is deleted or banned. It would make things much clearer and avoid having messages sitting in your inbox that you can't actually open.
It would just need to be added to the site's work schedule, as we're always busy working on different improvements and fixes. I'll speak to hiccupx about it and see if we can get it added to the list.
c00kie
FF Team
17 hours