Mail may quit when you view an email message that is malformed or damaged, and it may continue to quit as long as the message remains selected. Resolve the issue by following these steps to delete the message:
- Open Mail and immediately hold the Shift key until Mail opens. This causes Mail to open without any message or mailbox selected.
- Hide the message viewer portion of the window by carefully dragging the thin separator bar between it and your list of messages. Keep dragging until Mail shows only the list of messages, not the message viewer. In this view, you can see messages only by double-clicking to open the message.
- Click the affected message once to select it without opening it. Then press Delete or choose Message > Move to > Trash.