One of our clients is using Microsoft Online Exchange (BPOS)
The Blackberry users are getting old emails as new on a roughly weekly basis.
They will get a burst of what appears to be new email sometimes up to 6 months worth of old emails. Then at some point later on these will reconcile and dissapear. The carrier is Verizon they are blaming MS and MS is blaming the carrier. Anyone know who what is causing this??

Thank You!
JP

Mail left on the server ?

Cached Exchange Mode is designed to sync with the PC but it needs to create a folder. If no such folder can be created the sync may be causing this. Maybe because they have not determined the device doing the download such as the BB and as Dubdub indicated , it may be the server is sending email left on the server.
It might be worth calling the server support group and asking about the options.

Yes the Email is left on the server. But should only be sent to the BB once not repeatedly. The BB's are configured to use Exchange\Exchange active sync via the BPOS owa page...