Various options control how the messages are shown and how the display is organized.
The default value for the Display/Tags menu entry. When set to "Yes", a panel with a button for each tag is shown, each button being set when the corresponding tag is assigned to the message currently selected.
The default value for the Display/Headers menu entry. "None" means not to display any message header at all, "Most" means the most useful (From, To, Cc, Date...), and "All" means the full headers text.
Tells what should displayed in the "From" column of message lists: either the name of the sender (when known), or the email address.
When a message has both HTML and Text alternative representations, this option indicates which format should be shown first in the message pane. Text is the most secure choice.
When all messages of a list have the Sent
status, the Sender column is automatically switched to a Recipient column when this option is set to Yes. The column is switched back automatically to Sender when the list contents change, or manually with the context menu of the columns headers.
when set to Yes, URLs in the body panel appear as clickable links. The browser may need to be configured in the Paths sections.
The default value for the Display/Threaded menu entry. When set to "Yes", the messages that belong to a same thread are shown in tree-like representation, and the threads can be opened and closed.
How the dates are displayed in the message lists. Choose DD/MM/YYYY HH:MI or YYYY/MM/DD HH:MI depending on what you find the more easy to read.
The contextual popup menu of a message on display has a command fetching the last messages of the same sender than the mail currently shown. This setting tells how much of these messages this command should retrieve in one go.
The Qt library has several builtin styles (the actual list depends on the platform the interface is running on). The style controls the overall look of the interface as well as some usability tips, such as the function of the middle mouse button. Just try different styles and keep the one you like the most.