Thank you for your answer, but I wouldn't think it is a permission issue.
Permissions are set correctly afaik (vmail:vmail 755)
The problem is that maildrop tries to deliver to the wrong place.
If there is a /var/vmail folder mails are arrives there.
However they should arrive to /home/vmail.
I don't know where else I could set the delivery location.
As I read by default it should deliver to the home directory of the user (vmail)
Which is set to /home/vmail
Thanks a lot!