Mail and problems with read/unread status

Hi,

the title introduces the issues I have already... Mail, wich I am running in version 7.3 (1878.2) has problems to realise that I read some emails. The status simply stays as unread. It doesn't matter how often I open the email, I have to change the status by hand.

Does somebody else has this same problem and/or does somebody have a solution for the problem?

Cheers, Tom