Quartz

The model that sorts your inbox and drafts your replies runs locally on your Mac, not on a remote server. Your mail never gets uploaded, and the company can't read it because there's nothing stored on its side to read. That's a real difference from most AI email tools, which ship your messages off to a cloud provider and hope you don't think about where they end up sitting. The trade-off is that you need an Apple Silicon chip to run it.

Quartz auto-categorizes every message by importance, and the definition of "important" is yours. It learns over time from how you interact with senders. Important mail gets visual room, while FYI, Icebox, and Noise categories collapse out of the way. In practice, you spend less time scrolling and more time answering the threads that matter. So what does that look like on a busy Tuesday? You open the app and see maybe eight threads. Everything else is folded away. The categories are worth setting up early, because a model that guesses wrong about what counts as noise will quietly bury a message you actually needed to see that morning.

Give Quartz a few bullet points and it drafts a reply that sounds like you. It picks up your cadence, your phrasing, and how warm or terse you tend to be with a given sender. It reads the thread context, too, plus your relationship with the person. So the output avoids the flat, generic tone most AI assistants fall into. No robot voice here. That's the part most AI writing tools miss, since a draft only helps if you can send it without rewriting every sentence from scratch to sound like a human wrote it.

Mail is encrypted on your device with keys only you hold. Combined with on-device processing, that means neither the developer nor any AI provider touches your messages in readable form. For anyone who's uneasy about feeding work email into a chatbot, this is a big deal. It's the feature that makes Quartz, as a private email app, worth a look. Encryption on your device only helps as much as the device itself stays secure, so keep your Mac locked and your account protected like you would with any mail client.

Quartz is independently audited and certified under Google's Cloud Application Security Assessment at Tier 2. That's a third-party check on how the app handles Gmail data, not just a promise from the developer. It matters if you're weighing a new email client that wants access to your whole inbox, because an outside auditor has already looked at how it treats that access. Third-party review beats a marketing page every time.