These symbols may appear next to the message number for each message you recieve. D Mail you want to delete when you exit. If there is no symbol, then the message has been read and there is no action pending on that particular message. The menu at the bottom of the screen describes actions you may take with each message. Explore the entire menu to see your options.
Many menus have several rows of available options.
D Mark a message for deletion . It will not actually be erased until you expunge your messages. S Save message in the selected folder. After you type in the folder name and Orion asks you if you want to create the folder, hit Y for yes. F Forward the message to another address.