Version:            (using KDE 4.4.2)
OS:                Linux
Installed from:    Ubuntu Packages

When a message is deleted in the message list, the cursor goes down to the following row and the messages above the previously selected row go down. This behavior is repeated until the cursor reaches the last row in the messages list pane, preventing the user to see the following messages unless he manually scrolls the message list contents.
Instead, the cursor should be kept in the row that was selected before the user deleted the message and the following messages should go up. I think this is the expected behavior for most users.
Example:
Imagine you have a message list sized to display ten rows and the selected row is #5. So, there are four more rows being displayed before the selected one and five after. If you click DEL, the message in the selected row is deleted. After this, I think most users would expect that the fifth row would still be the selected one. There should still be four rows visible before it and five after. Messages that were in rows 6 to 10 would be scrolled up to rows 5 to 9 and a new message would be displayed in row 10. So you would always see the following five messages after the one that is currently selected.
But this is not what happens. After deleting message in row #5, the cursor goes to row 6. Messages that were in rows 1 to 4 are scrolled down to rows 2 to 5 and one new message is displayed in row 1. You have now 5 messages before the cursor and 4 after. Deleting more messages will make the cursor eventually reach row #10 and now you can't see in advance the next messages anymore. This is a very odd behavior and makes it difficult to manage messages in folders which hold very active discussion lists, for example. In folders such as this, several messages are commonly deleted in a row if their subjects are of no interest to the user and not being able to see the next messages slows down the process of deleting messages significantly.