iNotes/ Notes Client - unread messages

Some of our users access mail via iNotes as well as Notes Client.

Once they have read messages on the client they still appear as unread on iNotes (or vice versa).

I know how to exchange unread marks between local and server replica but how do we do it for iNotes Vs Notes Client?

Why does this happen ? Is there any way to prevent this from happening ?

Thanks for any help …