Hey there on more question.
The Mail app Version 0.5.2 is enabled and I have one Account in there. I encountered that if I get new Mails an read them the Mail App does not automatically update the number of unread Mail in the first column where the Inbox is located.
Only to manually load the site again or press F5 will do that. Is this a known Problem?
I will write a bug report there. Thanks!