I have recently successfully transitioned Exchange 2003 to Exchange 2010. Everything is going fine except users who are using Outlook Express 6.0. I know that Outlook Express is not recommended mail client for Exchange 2010, but we have many users who are currently having Outlook Express configured and we are planning to move to MS Outlook 2010.
When Outlook Express is closed and reopened it downloads same email address multiple times. I have already gone through the knowledge base http://support.microsoft.com/kb/245620
and don't want to remove "Leave a copy of messages on server" option in Outlook, because in this case users won't be able to get theire downloaded messages using Outlook Web Access (OWA).
I didn't have any problem when with Exchange 2003, but after upgrading this to Exchange 2010 facing this type of typical problem.
Need your help.