30 days after you start using Apple’s Mail app version 7 on Mavericks with your Gmail account you’re going to start losing emails.
Let me explain.
Google’s recommended IMAP client settings tell Apple Mail users to leave unchecked the “Move deleted messages to the Trash mailbox” option (in Preferences > Accounts > Mailbox Behaviors). Why? Gmail users expect “deleted” messages to be archived, not deleted. Emails marked as Trash, however, are deleted by Gmail after 30 days.
Prior to Apple Mail 7—the one that comes with Mavericks—it was possible to follow Google’s recommend client settings to make everything work as a Gmail user would expect.
The problem is, with Apple Mail 7, it seems to be impossible to uncheck to the “Move deleted messages to the Trash folder” option in Mail > Preferences > Accounts > Mailbox Behaviors.
As a result, when you delete a message, Apple Mail gives it the Trash label and Gmail deletes it 30 days later. Note that the “Permanently erase deleted messages when” option applies to Apple Mail’s behavior, not Gmail’s behavior.
What’s alarming is this: I had my IMAP settings correctly configured according to Google’s recommendations with the previous version of Apple Mail and upgrading to Mavericks silently changed the settings.
Without warning, Apple Mail started marking my deleted messages as Trash, setting them up to be reaped by Gmail after 30 days!
Fortunately for me, an entirely unrelated and repeatable data-loss bug in Apple Mail 7 forced me to go digging into my Gmail account via the Gmail web interface this evening. That’s when I discovered things in the trash that I didn’t expect to be there. Since I’ve been less than 30 days on Mavericks, I didn’t lose any email and was able to remove the Trash label. I got lucky. (The unrelated data-loss bug, while horrendous, is something that most people are unlikely to stumble upon so I’m not raising the alarm on it. I have reported it to Apple.)
Long story short, if you use the new Apple Mail + Gmail then the clock is ticking on emails that you’d never expect to be permanently deleted.