I have a laptop, and I also have a Blackberry mobile fone. I receive and read/send my emails on both. Last night I was on my laptop and decided to have a bit of a clean up of my hotmail account so I deleted about 200-250 emails.
Ive woken up today, turned on my Blackberry and every single deleted email is back in my email account on my fone, as unread.
Probably because your Blackberry downloads the emails onto your phone. You then delete them from Hotmail, but they are still on your phone. My guess is that when the Blackberry syncs with your Hotmail account, it sees a lot of messages which are not on your Hotmail account and assumes they are new messages, so marks them as unread.
Hmmm, well there is only about 3 months worth of emails on BB, but 5 years worth on laptop. it was really old ones I deleted on laptop which have never been on BB.