How do I stop loading images in Junk mail folder in Mail.app 6.6 with Gmail
You have to "map" the Gmail folders to match what happens in Mail.app.


Open Preferences in Mail.app
Go to Accounts and select your Gmail account
Click the "Advanced" tab
Enter [Gmail] (yes, with the brackets) into the 'IMAP Path Prefix' field
Close the window and Save changes to the Account.