The mailboxes to include in the count of unread messages (the red circle, called a badge, that’s shown on the Mail icon in the Dock).
To hear sounds for other events in Mail, select the “Play sounds for other mail actions” checkbox. To sample a sound, click the pop-up menu, then choose a sound.
The sound to play when you receive messages. (Whenever you click an IMAP or Exchange mailbox in the Mail sidebar, it syncs with the server, and shows new messages.) If you change the option to Manually, click the Get Mail button in the Mail toolbar to check for messages. By default, the option is set to Automatically (Mail varies how often it gets messages based on whether your Mac is plugged into an electrical outlet). When Mail gets new messages from the mail server.
