Multiple emails from forum subscriptions

I'm subscribed to a few threads in the forums so I get email notifications when there are new posts - which is great, exactly what I need. However, I often get multiple emails notifying the same post. Once I got home from work to find 15 emails from Gallery and there were just 2 new posts in the relevant thread! I've also had a notification email a couple of times quite a while after I've already visited the forums and read the new posts.

Is this a known issue? Is there any fix?

Thanks!