Oldest emails being "reopened" by device

[Photografeeman]

This is my 3rd smartphone and first Samsung. For some reason, the oldest emails in my inbox, will re-classify themselves as not having been opened. I get notified of new email and see the only unopened ones are the oldest. If I do nothing, in time, more of them get reclassified the same way. If I open them, within a few hours it will start again.

I have upgraded to Kitkat 4.3, deleted and reconfigured all email accounts, 5 chats with Samsung tech service and I still have this issue which has been going on for months. Is it me or is this a Samsung issue?