One of the websites that I use regularly has a built-in messaging feature. Whenever someone sends you a message, it appears in a special area where you can reply, delete, etc. The site also tries to notify you when new messages come in. The problem is, these notifications are always wrong. For example, if I have three new messages, it might tell me I have five.

I’m sure there’s some complex technical reason why the numbers don’t match up. Maybe it’s legacy code that will take years to update. So my advice to developers is simple: if you can’t provide an accurate tally, don’t give any numbers at all. Saying “You have messages” is almost as useful as giving the exact number, especially if those numbers aren’t accurate in the first place. In other words, err on the side of less information if you can’t be sure that the underlying data will match up.