Is there any switch just to see only the unread messages in the Email-app ??
no there is no such switch. What sense would it make?
The switch makes sense.....
If you have a some mails in your inbox, you can quickly just select the mails
you still have to read/to answer.
There also often Spams with a false date, which will bei sortet in very deep
in your mails.
Its an easy way to find them.
In Thundebird or egroupware there is such a switch.
you can sort for read/unread status, or just move mails you don't want to see to another folder. However, please contact open-xchange through http://www.open-xchange.com/en/contactus for feature requests or code contributions of such a feature.