The only way to get eM Client to delete and go to the next newest message is to have it show new messages at the bottom. Showing new messages at the top makes it go to the next *older* message after deleting the message being read. The only way that setup works is for people who never ever leave any read messages in their inbox - so with no older message to go to, the client is forced to go to the next message in order, which has become the new first message.
Those two functions should be separated so if for some reason a user wants to read their mail in reverse chronological order and have new messages at the bottom, they can - or if they want new messages at the top and be able to go through their messages in chronological order, they can do it that way.
A second choice alternative would be to automatically scroll to the oldest unread message. As it is I have to set it to new messages at the bottom then scroooooooolllll down through my old inbox messages to get to the oldest unread one.