Actually, the bugs in Mavericks Mail (for Gmail users and Google Apps users) get even worse:
Mail no longer recognizes custom-mapped folders for "Sent Mail" and "Trash". Mail in Mavericks FORCES deleted messages to go into Google's Trash, instead of the custom-mapped folder that you might have created for yourself.
This is terrible, because if you use Google's Trash, your deleted messages will automatically delete after 30 days. But if you use your own custom-mapped Trash folder, then you can keep your deleted messages around forever.
Furthermore, if you DO try to use a custom-mapped folder in Mail, those folders will appear compeltely BLANK in Mail, even if they already contain thousands of messages in them. So you can't even go back and look at your previously-trashed messages from before Mavericks! You have to log into the Gmail website.
Terrible!