I receive my outlook email on my Blackberry. If I do anything with an email on the computer it will resend the message to my Blackberry.
Soooo...
The message will come in
If I flag it on the computer it resends it to my Blackberry
Then later I reply to it, it resends it to my Blackberry
If I forward it, it resends it to my Blackberry
And finally when I unflag it, it resends it to my Blackberry
This means I may have the same message come in on my phone up to FIVE times. It's really annoying and nobody seems to have any idea what to do to fix it.