Tagging email as unread does not work

Hi all,

I use to preview my email on the iPhone but I would like to let them tagged as unread because I do the real email processing on my desktop computer.

Unfortunately:

1) there is not an iPhone setting that would allow me to look at the email content without tagging them as read (why? It would be so easy and comfortable!);

2) once I have read an email I swipe from left to right to tag it as unread. Most of the times this has no effect (the blue dot appears but if I refresh the screen it disappears and, of course, I do not see that email as unread on the desktop computer anymore).

Is that normal? Is there any workaround?

Thanks in advance.

PS: I use Microsoft Exchange, Gmail and Apple accounts and it seems that my problem spreads on them indifferently.